Contents

**NEET Physics Chapter Wise Mock Test – Current Electricity**

**Question 1:
**The plot represents the flow of current through a wire at three different times. The ratio of charges flowing through the wire at different times is (see figure)

**(a) 2:1:2**

(b) 1:3:3

(c) 1:1:1

(d) 2:3:4

**Question 2:
**A uniform copper wire of cross-sectional area 2 mm

^{2}carries a steady current of 10 A. The density of free electrons in copper is 8 x 10

^{28}m

^{-3}. The drift velocity of electrons is nearly

(a) 4×10

^{-4}ms

^{-1}

(b) 2 x 10

^{-4}ms

^{-1}

(c) 4x1O

^{-2}ms

^{-1}

(d) 2 x 10

^{-2}ms

^{-1}

**Question 3:
**The current density at a point in a uniform copper wire of area of cross-section 2.5 mm

^{2}carrying a steady current of 1 nA is

(a) 4 x 10

^{-4}Am

^{-2}

(b) 25 x 10

^{-4}Am

^{-2}

(c) 1.25 x 10

^{-3}Am

^{-2}

(d) 4 x 10

^{-3}Am

^{-2}

**Question 4:
**A cylindrical conductor AB of non-uniform area of cross-section carries a current of 5 A. The radius of the conductor at one end A is 0.5 cm. The current density at the other end of the conductor is half of the value at A The radius of the conductor at the end B is nearly

(a) 1.4 cm

(b) 0.7 cm

(c) 0.6 cm

(d) None of these

**Question 5:
**The current density at every point in a uniform conductor is 4×10

^{8}Am

^{-2}. The drift velocity of electrons in the conductor is 2 x 10

^{-4}ms

^{-1}. The carrier charge density is

(a) 2 x 10

^{12}Cm

^{-3}

(b) 2 x 10

^{18}Cm

^{-3}

(c) 0.5 x 10

^{8}Cm

^{-3}

(d) None of these

**Question 6:
**Consider a current carrying wire (current I ) in the shape of a circle. Note that as the current progresses along the wire, the direction of J (current density) changes in an exact manner, while the current l remains unaffected. The agent that is essentially responsible for is

(a) source of emf

(b) electric field produced by charges accumulated on the surface of wire

(c) the charges just behind a given segment of wire which push them just the right way by repulsion

(d) the charges ahead

**Question 7:
**Which of the following characteristics of electrons determines the current in a conductor?

(a) Drift velocity alone

(b) Thermal velocity alone

(c) Both drift velocity and thermal velocity

(d) Neither drift nor thermal velocity

**Question 8:
**A metal rod of the length 10 cm and a rectangular cross-section of 1 cm x 1/2 cm is connected to a battery across opposite faces. The resistance will be

(a) maximum when the battery is connected across 1 cm x 1/2 cm faces

(b) maximum when the battery is connected across 10 cm x 1cm faces

(c) maximum when the battery is connected across 10 cm x 1/2 cm faces

(d) same irrespective of the three faces

**Question 9:
**If each resistance in the figure is of 9Ω, then reading of ammeter is

**(a) 5 A**

(b) 8 A

(c) 2 A

(d) 9 A

**Question 10:
**When a wire of uniform cross-section a, length Z and resistance R is bent into a complete circle, resistance between two of diametrically opposite points will be

(a) R/4

(b) R/8

(c) 4R

(d) R/2

**Question 11:
**The effective resistance between A and B in figure is

**(a) 2 Ω**

(b) 3 Ω

(c) 5 Ω

(d) 6 Ω

**Question 12:
**Each of the resistors showing in figure has resistance R. Find the equivalent resistance

**(a) 7R/4**

(b) 5R/4

(c) 9R/4

(d) 11R/4

**Question 13:
**A spherical shell, made of material of electrical conductivity 10

^{9}/π (Ωm)

^{-1}, has thickness t = 2mm and radius R = 10cm. In an arrangement, its inside surface is kept at a lower potential than its outside surface. The resistance offered by the shell is equal to

**(a) 5π x 10**

^{-12}Ω

(b) 2.5 x 10

^{-11}Ω

(c) 5 x 10

^{-12}Ω

(d) 5 x10

^{-11Ω}

**Question 14:
**The length of a conductor is halved. Its conductivity will be

(a) halved

(b) unchanged

(c) doubled

(d) quadrupled

**Question 15:
**The resistance of a wire at 20°C is 20 Ω and at 500°C is 60 Ω. At which temperature its resistance will be 25 Ω?

(a) 50°C

(b) 60°C

(c) 70°C

(d) 80°C

**Question 16:
**A resistance coil and a battery are given. In which of the following cases the heat generated is maximum?

(a) When the coil is directly connected to the battery as such

(b) When the coil is divided into two equal parts and both parts are connected to the battery in parallel

(c) When the coil is divided into four equal parts which are . connected to the battery in parallel

(d) When only half the coil is connected to the battery

**Question 17:
**Two lamps P and Q are connected in parallel in an electric circuit. Lamp P glows brighter than lamp Q. If R

_{P}and R

_{Q}are their respective resistances, then

(a) R

_{P}> R

_{Q}

(b) R

_{P}< R

_{Q}

(c) R

_{P}= R

_{Q}

(d) None of these

**Question 18:
**The total power consumed by 100 W and 200 W bulbs connected in series across a 220 V mains is

(a) 66.7 W

(b) 82.4 W

(c) 150 W

(d) 300 W

**Question 19:
**Three equal resistors connected in series across a source of emf together dissipate 10 W power. If the same resistors are connected in parallel across the same source, the power dissipated will be

(a) 90 W

(b) 10/3W

(c) 30 W

(d) 10W

**Question 20:
**A house wiring, supplied with a 220 V supply line is protected by a 9 A fuse. The maximum number of 60 W bulbs in parallel that can be turned on, is

(a) 44

(b) 33

(c) 22

(d) 11

**Question 21:
**Two heater coils separately take 10 min and 5 min to boil a certain amount of water. If both the coils are connected in series, the time taken will be

(a) 2.5 min

(b) 3.33 min

(c) 7.5 min

(d) 15 min

**Question 22:
**In the circuit shown, the heat produced in 5ohm resistor is 10 cals

^{-1}. The heat produced per sec in 4Ω resistor will be

**(a) 1 cal**

(b) 2 cal

(c) 3 cal

(d) 4 cal

**Question 23:
**Two electric bulbs, each designed to operate with a power of 500 W in 220 V line are connected in series in a 110 V line. The power generated by each bulb will be

(a) 11 W

(b) 312.5 W

(c) 22W

(d) 31.25 W

**Question 24:
**An electric kettle has two heating coils. When one of the coils is connected to an AC source, the water in the kettle boils in 10 min. When the other coil is used the water boils in 40 min. If both the coils are connected in parallel, the time taken by the same quantity of water to boil will be

(a) 8 min

(b) 4min

(c) 25 min

(d) 15 min

**Question 25:
**In a copper voltmeter, the mass deposited in 30 s is mgram. If the current-time graph as shown in the figure, the ECE of copper, in gC

^{-1}, will be

**(a) m**

(b) m/2

(c) 0.6m

(d) 0.1m

**Question 26:
**If 100 kWh of energy is consumed at 33 V in a copper voltmeter, the mass of copper liberated is

(Given ECE of copper = 3.3 x 10

^{-7}kgC

^{-1})

(a) 1.65 kg

(b) 1.8 kg

(c) 3.3 kg

(d) 3.6 kg

**Question 27:
**A silver and a zinc voltmeters are connected in series. A current is passed through them for time t. If w gram zinc is liberated, then the weight of silver deposited will nearly be

(a) 3.3w

(b) 2.4w

(c) 1.7w

(d) w

**Question 28:
**A cell of emf 1.5 V having a finite internal resistance is connected to a load resistance of 2Ω. For maximum power transfer the internal resistance of the cell should be

(a) 4Ω

(b) 0.5Ω

(c) 2Ω

(d) None of these

**Question 29:
**The number of dry cells each of emf 1.5 V and internal resistance 0.5Ω that must be joined in series with a resistance of 20Ω so as to send a current of 0.6 A through the circuit is

(a) 2

(b) 8

(c) 10

(d) 12

**Question 30:
**Two cells having the same emf, are connected in series through an external resistance R. Cells have internal resistances r

_{1}and r

_{2}(r

_{1}> r

_{2}), respectively. When the circuit is closed, the potential difference across the first cell is zero. The value of R is

(a) r

_{1}– r

_{2}

(b) (r

_{1}+r

_{2})/2

(c) (r

_{1}– r

_{2})/2

(d) r

_{1}+ r

_{2}

**Question 31:
**Two batteries, one of emf 18 V and internal resistance 2Ω and the other of emf 12 V and internal resistance 1Ω, are connected as shown in figure. The voltmeter V will record a reading of

**(a) 15 V**

(b) 30 V

(c) 14V

(d) 18V

**Question 32:
**When the resistance of 9ohm is connected at the ends of a battery, its potential difference decreases from 40 V to 30 V. The internal resistance of the battery is

(a) 6Ω

(b) 3Ω

(c) 9Ω

(d) 15Ω

**Question 33:
**

**Question 34:
**A 50 V battery is connected across 10Ω resistor. The current is 4.5 A. The internal resistance of the battery is

(a) zero

(b) 0.5Ω

(c) 1.1Ω

(d) 5.0Ω

**Question 35:
**In figure, value of current I is

**(a) 1.5 A**

(b) 0.4 A

(c) 0.9 A

(d) 0.7 A

**Question 36:
**In figure values of l

_{x}and l

_{y}are respectively

**(a) 1A, 1A**

(b) 1.2A, 1.2A

(c) 0.8A, 0.8A

(d) 1A, 1.2A

**Question 37:
**In figure E is equal to

**(a) 5V**

(b) 4V

(c) 3V

(d) 2 V

**Question 38:
**In the given circuit, find the potential difference across 6 μF capacitor in steady state

**(a) 4V**

(b) 2V

(c) 6V

(d) None of above

**Question 39:
**In the Wheatstone’s bridge shown in figure, where P = 2Ω, Q = 3Ω, R=6Ω and S = 8Ω. In order to obtain balance, shunt resistance across S must be

**(a) 2Ω**

(b) 3Ω

(c) 6Ω

(d) 8Ω

**Question 40:
**The resistance of each arm of the Wheatstone’s bridge is 10Ω. A resistance of 10Ω is connected in series with galvanometer, then the equivalent resistance across the battery will be

(a) 10Ω

(b) 15Ω

(c) 20Ω

(d) 40Ω

**Question 41:
**Thirteen resistances each of resistance R Ω are connected in the circuit as shown in the figure below. The effective resistance between A and B is

**(a) R Ω**

(b) 2R/3 Ω

(c) 4R/3 Ω

(d) 2R Ω

**Question 42:
**In a meter bridge, the balancing length from the left end (standard resistance of one ohm is in the right gap) is found to be 20 cm. The value of the unknown resistance is

(a) 0.8Ω

(b) 0.5Ω

(c) 0.4Ω

(d) 0.25Ω

**Question 43:
**Sensitivity of potentiometer can be increased by

(a) increasing the emf of the cell

(b) increasing the length of the potentiometer wire

(c) decreasing the length of the potentiometer wire

(d) None of the above

**Question 44:
**Two cells of emfs approximately 5V and 10V are to be accurately compared using a potentiometer of length 400 cm.

(a) The battery that runs the potentiometer should have voltage of 8 V

(b) The battery of potentiometer can have a voltage of 15 V and R adjusted so that the potential drop across the wire slightly exceeds 10 V

(c) The first portion of 50 cm of wire itself should have a potential drop of 10 V

(d) Potentiometer is usually used for comparing resistances and not voltages

**Question 45:
**For a cell of emf 2V, a balance is obtained for 50 cm of the potentiometer wire. If the cell is shunted by a 2oΩ resistor and the balance is obtained across 40 cm of the wire, then the internal resistance of the cell is

(a) 0.025Ω

(b) 0.50Ω

(c) 0.80Ω

(d) 1.00Ω

**Question 46:
**If specific resistance of a potentiometer wire is 10

^{-7}Ωm and current flow through it is 0.1 A,cross-sectional area of wire is 10

^{-6 }m

^{2}, then potential gradient will be

(a) 10

^{-2}Vm

^{-1}

(b) 10

^{-4}Vm

^{-1}

(c) 10

^{-6}Vm

^{-1}

(d) 10

^{-8}Vm

^{-1}

**Question 47:
**Figure shows a simple potentiometer circuit for measuring a small emf produced by a thermocouple

**The meter wire PQ has a resistance of 5Ω and the driver cell an emf of 2.00 V. If a balance point is obtained 0.600 m along PQ when measuring an emf of 6.00 mV, what is the value of resistance R?**

(a) 95Ω

(b) 995Ω

(c) 195Ω

(d) 1995Ω

**Question 48:
**A galvanometer of resistance 100Ω gives full scale deflection for 10 mA current. What should be the value of shunt so that it can measure a current of 100 mA?

(a) 11.11 Ω

(b) 9.9 Ω

(C) 1.1 Ω

(d) 4.4 Ω

**Question 49:
**A galvanometer of resistance 100Ω gives full scale deflection for a current of 10

^{-5}A. The shunt required to convert it into an ammeter of 1 A range will be

(a) 10

^{-2}Ω

(b) 1Ω

(c) 10

^{-1}Ω

(d) 10 Ω

**Question 50:
**The range of a voltmeter of resistance G Ω is V volt. The resistance required to be connected in series with it in order to convert it into a voltmeter of range nV volt, will be

(a) (n-1)G

(b) G/n

(c) nG

(d) G/(n -1)

**Question 51:
**

**Question 52:
Assertion (A): **The resistance of an ideal voltmeter should be infinite.

**The lower resistance of voltmeters gives a reading lower than the actual potential difference across the terminals.**

Reason (R):

Reason (R):

(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion

(b) If both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion

(c) If Assertion is true but Reason is false

(d) If both Assertion and Reason are false

**Question 53:
**A potentiometer wire has length 4 m and resistance 8 Ω. The resistance that must be connected in series with the wire and an accumulator of emf 2 V, so as to get a potential gradient 1 mV per cm on the wire is

(a) 32 Ω

(b) 40 Ω

(c) 44 Ω

(d) 48 Ω

**Question 54:
**

**Question 55:
**Across a metallic conductor of non-uniform cross-section a constant potential difference is applied. The quantity which remains constant along the conductor is

(a) current density

(b) current

(c) drift velocity

(d) electric field

**Question 56:
**Two cities are 150 km apart. Electric power is sent from one city to another city through copper wires. The fall of potential per km is 8 V and the average resistance per km is 0.5 Ω. The power loss in the wire is

(a) 19.2 W

(b) 19.2 kW

(c) 19.2 J

(d) 12.2kW

**Question 57:
**The resistance in the two arms of the meter bridge are 5 Ω and R Ω, respectively. When the resistance R is shunted with an equal resistance, the new balance point is at 1.6l

_{1}. The resistance R, is

**(a) 10 Ω**

(b) 15 Ω

(c) 20 Ω

(d) 25 Ω

**Question 58:
**A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire, has an emf of 2.0 V and a negligible internal resistance. The potentiometer wire itself is 4 m long. When the resistance, R connected across the given cell, has values of

(i) Infinity (ii) 9.5 Ω

The ‘balancing length’, on the potentiometer wire are found to be 3 m and 2.85 m, respectively. The value of internal resistance of the cell is

(a) 0.25 Ω

(b) 0.95 Ω

(c) 0.5 Ω

(d) 0.75 Ω

**Question 59:
**In the electric circuit shown each cell has an emf of 2V and internal resistance is 1 Ω. The external resistance is 2 Ω. The value of the current I is (in ampere)

**(a) 2**

(b) 1.25

(c) 0.4

(d) 1.2

**Question 60:
**A wire of resistance 4 Ω is stretched to twice its original length. The resistance of stretched wire would be

(a) 2 Ω

(b) 4 Ω

(c) 8 Ω

(d) 16 Ω

**Question 61:
**The internal resistance of a 2.1 V cell which gives a current of 0.2 A through a resistance of 10 Ω is

(a) 0.2 Ω

(b) 0.5 Ω

(c) 0.8 Ω

(d) 1.0 Ω

**Question 62:
**The resistance R, of a conductor varies with temperature t as shown in figure. If the variation is represented by

R

_{t}= R

_{0}(1 + αt + βt

^{2}). Then,

**(a) α and β both negative**

(b) α is positive and β is negative

(c) α and β both are positive

(d) α is negative and β is negative

**Question 63:
**A 100 V voltmeter of internal resistance 20 kΩ in series with a high resistance R is connected to 110 V line. The voltmeter reads 5V, the value of R is

(a) 210 kΩ

(b) 315 kΩ

(c) 420 kΩ

(d) 4440 kΩ

**Question 64:
**6 Ω and 12 Ω resistors are connected in parallel. This combination is connected in series with a 10 V battery and 6 Ω resistor. What is the potential difference between the terminals of the 12 Ω resistor?

(a) 4 V

(b) 16 V

(c) 2 V

(d) 8 V

**Question 65:
**Charge passing through a conductor of cross-section area A = 0.3 m

^{2}is given by q = 3t

^{2}+ 5t + 2 in coulomb, where t is in second. What is the value of drift velocity at t = 2s? (Given, n = 2 x 10

^{25}/m

^{3})

(a) 0.77 x 10

^{-5}m/s

(b) 1.77 x 10

^{-5}m/s

(c) 2.08 x 10

^{5}m/s .

(d) 0.57 x 10

^{5}m/s

**Question 66:
**A generator at a utility company produces 100 A of current at 4000 V. The voltage is stepped upto 240000 V by a transformer before it is sent on a high voltage transmission line. The current in transmission line is

(a) 3.67 A

(b) 2.67 A

(c) 1.67 A

(d) 2.40 A

**Question 67:
**A 5.0 A current is set up in an external circuit by a 6.0 V storage battery for 6.0 min. The chemical energy of the battery is reduced by

(a) 1.08 x 10

^{4}J

(b) 1.08×10

^{-4}J

(c) 1.8×10

^{4}J

(d) 1.8 x 10

^{-4}J

**Question 68:
**If voltage across a bulb rated 220 V-100 W drops by 2.5% of its rated value, the percentage of the rated value by which the power would decrease is

(a) 20%

(b) 2.5%

(c) 5%

(d) 10%

**Question 69:
**A ring is made of a wire having a resistance R

_{0}= 12Ω. Find the points A and B, as shown in the figure, at which a current carrying conductor should be connected so that the resistance R of the sub circuit between these points is equal to 8/3 Ω.

**Question 70:
**A resistor of 6 kΩ with tolerance 10% and another of 4 kΩ with tolerance 10% are connected in series. The tolerance of combination is about

(a) 5%

(b) 10%

(c) 12%

(d) 15%

**Question 71:
**Two bulbs 40 W and 60 W and rated voltage 240 V are connected in series across a potential difference of 420 V. Which bulb will work at above its rated voltage?

(a) 40 W bulb

(b) 60 W bulb

(c) Both will work

(d) None of these

**Question 72:
**A current of 2 A flows through a 2 Ω resistor when connected across a battery. The same battery supplies a current of 0.5 A when connected across a 9 Ω resistor. The internal resistance of the battery is

(a) 1/3 Ω

(b) 1/4 Ω

(c) 1 Ω

(d) 0.5 Ω

**Question 73:
Assertion (A): **The value of temperature coefficient of resistance is positive is for metals.

**The temperature coefficient of resistance for insulator is also positive.**

Reason (R):

Reason (R):

(a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion

(b) If both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion

(c) If Assertion is true but Reason is false

(d) If both Assertion-and Reason are false

**Question 74:
**When a copper voltmeter is connected with a battery of emf 12 V. 2g of copper is deposited in 30 min. If the same voltmeter is connected across a 6 V battery, then the mass of copper deposited in 45 min would be

(a) 1 g

(b) 1.5 g

(c) 2g

(d) 2.5g

**Question 75:
**If two bulbs of wattages 25 W and 100 W respectively each rated by 220 V are connected in series with the supply of 440 V. Which bulb will fuse?

(a) 100 W bulb

(b) 25 W bulb

(c) Both of them

(d) None of these

### Answers:

### Hints And Solutions: