NEET Physics Chapter Wise Mock Test – Electrostatics and Current Electricity
A conducting loop has a charge of q = 4 μC. The thickness of the loop is negligible and its radius is r = 6 cm. What is the electric field (E) on the axis of symmetry of the loop at a distance of x = 8 cm from the centre of the loop?
(a) 288 x 102 Vm-1
(b) 288 x 103 Vm-1
(c) 288 x 104 Vm-1
(d) 288 x 105 Vm-1
Eight dipoles of charges of magnitude e are placed inside a cube. The total electric flux coming out of the cube will be
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 I 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 charge ahead
Two conductors A and B of the same length and radius are connected across the same battery. Resistivity of A is twice that of B. If PA and PB be the powers dissipated across A and B respectively, then
(b) PA >PB
(c) PA < PB
(d) None of these
Electric potential at any point V = – 5x + 3y + √15z, then the magnitude of the electric field is
Eight mercury droplets having a radius of 1 mm and a charge of 0.066 pC each merge to have one droplet. Its potential is
(a) 2.4 V
(b) 1.2 V
(c) 3.6 V
(d) 4.8 V
A charged sphere of diameter 4 cm has a charge density of 10-4 C cm-3. The work done in joule when a charge of 40 NC is moved from infinity to a point which is at a distance of 2 cm from the surface of the sphere is
(a) 14.4 π
(b) 28.8 π
(c) 144 π
(d) 288 π
A current of 1.5 A flows through a copper voltmeter. The thickness of copper deposited on the electrode surface of area 50 cm2 in 20 min will be (Density of copper = 9000 kgm-3 and ECE of copper = 0.00033 g C-1)
(c) 1.3x 10-5 m
(d) 1.3×10-4 m
A charged particle q is shot towards another charged particle Q, which is fixed, with a speed v. It approaches Q up to a closest distance r and then returns. If q were given a speed of 2v, then closet distance of approach would be
Figure below shows six equal capacitors each of capacitance C connected to each other.
What will be the value of equivalent capacitance between A and B?
In the given circuit diagram, E = 5 V, r = 1 Ω, R2 = 4 Ω, R1 = R3 = 1 Ω and C=3 μF.
Then, what the numerical value of the charge on each plate of the capacitor?
(a) 24 μC
(b) 12 μC
(C) 6 μC
(d) 3 μC
Two cells of emfs approximately 5 V and 10 V 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 10V
(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
A 500 W heating unit is designed to operate on a 115 V line. If the line voltage drops to 110 V line, the percentage drop in heat output will be
A parallel plate capacitor is connected to a battery. The plates are pulled apart with a uniform speed. If x is the separation between the plates, the time rate of change of electrostatic energy of capacitor is proportional to
A 120 W, 60 V bulb is to be operated on a 120 V DC supply. For this a resistor of resistance R is connected in series with the bulb. The value of R is
(a) 60 Ω
(b) 30 Ω
(c) 90 Ω
(d) 100 Ω
Twenty identical bulbs are connected in series across a 220 V supply. Two of the bulbs are found to burn out. The remaining 18 bulbs are connected again in series across the same supply. The illumination will be
(a) the same in both the cases
(b) more with 20 bulbs than with 18 bulbs
(c) more with 18 bulbs than with 20 bulbs
(d) unpredictable as the given data is not sufficient
Five identical plates, each of area A are joined as shown in figure. The distance between the plates is d. The plates are connected to a potential difference V volt. The charge on plates 1 and 4 will be
(a) q and q
(b) q and +2q
(c) q and -2q
(d) q and 3q
In a potentiometer experiment the balancing with a cell is at length 240 cm. On shunting the cell with a resistance of 2 Ω, the balancing length becomes 120 cm. The internal resistance of the cell is
(a) 4 Ω
(b) 2 Ω
(c) 10 Ω
(d) 0.5 Ω
Electric bulbs 50 W-100 V glowing at full power are to be used in parallel with battery 120 V, 10 Ω. Maximum number of bulbs that can be, connected, so that they glow in full power is
Masses of 3 wires of same metal are in the ratio 1 : 2 : 3 and their lengths are in the ratio 3:2:1. The electrical resistances are in ratio
(a) 1:4: 9
(c) 1:2: 3
A uniform resistance wire of length L and diameter d has a resistance R. Another wire of same material has length 4L and diameter 2 d, the resistance will be
Direction(Q. NOs.26-31): In each of the following questions, a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements, mark the correct answer as
(a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion
(b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
(c) If Assertion true but Reason is false
(d) If both Assertion and Reason are false
Assertion (A): A parallel plate capacitor is connected across battery through a key. A dielectric slab of dielectric constant K is introduced between the plates. The energy which is stored becomes K times.
Reason (R): The surface density of charge on the plate remains constant or unchanged.
Assertion (A): If the distance between parallel plates of a capacitor is halved and dielectric constant becomes three times, then the capacitance becomes 6 times.
Reason (R): Capacity of the capacitor does not depend upon the nature of the material.
Assertion (A): When an insulated wire is bent, its resistivity increases.
Reason (R): On bending, the drift velocity of electron decreases.
Assertion (A): An electric bulb becomes dim, when an electric heater in parallel circuit is switched on.
Reason (R): Dimness decreases after some time.
Assertion (A): The power dissipated in a conductor of resistivity ρ is proportional to ρ-1
Reason (R): The expression for resistance of a conductor is given by R = ρl/A
Assertion (A): A thermoelectric refrigerator is based on the Peltier effect.
Reason (R): A thermocouple may be used as a radiation detector.
A spherical drop of capacitance 1 μF is broken into eight drops of equal radius. Then, the capacitance of each small drop is
(a) 1/2 μF
(b) 1/4 μF
(c) 1/8 μF
(d) 8 μF
A parallel plate capacitor filled with a material of dielectric constant K is charged to a certain voltage. The dielectric material is removed. Then,
1. the capacitance decreases by a factor K
2. the electric field reduces by a factor K
3. the voltage across the capacitor increases by a factor K
4. the charge stored in the capacitor increases by a factor K
(a) 1 and 2 are true
(b) 1 and 3 are true
(c) 2 and 3 are true
(d) 2 and 4 are true
The capacity of a con denser is 4×10-6 F and its potential is 100 V. The energy released on discharging it fully will be
(a) 0.04 J
(b) 0.02 J
(c) 0.025 J
(d) 0.05 J
A parallel plate capacitor having a plate separation of 2 mm is charged by connecting it to a 300 V supply. The energy density is
(a) 0.01 Jm-3
(b) 0.1 Jm-3
(c) 1.0 Jm-3
(d) 10 Jm-3
The capacity of an air condenser is 2.0 μF. If a medium is placed between its plates. The capacity becomes 12 μF. The dielectric constant of the medium will be
The capacitors A and B have identical geometry. A material with a dielectric constant 3 is present between the plates of B. The potential difference across A and B are respectively
(a) 2.5 V, 7.5 V
(b) 2 V, 8 V
(c) 8V, 2 V
(d) 7.5 V, 2.5 V
Between the plates of parallel plate capacitor of capacity C, two parallel plates of the same material and area same as the plate of the original capacitor, are placed. If the thickness of these plates is equal to 1/5th of the distance between the plates of the original capacitor, then the capacity of the new capacitor is
The effective resistance between A and B of the shown network, where resistance of each resistor is R, is
(d) None of these
For the potentiometer arrangement as shown in the figure, length of wire AB is 100 cm and its resistance is 9 Ω. Find the length AC for which the galvanometer G will show zero deflection.
(a) 66.7 cm
(b) 60 cm
(c) 50 cm
(d) 33.3 cm
In a practical Wheatstone bridge circuit, when one more resistance of 100 Ω is connected in parallel with unknown resistance x, then the ratio l1/l2 becomes 2. l1 is the balance length. AB is a uniform wire. Then, the value of x must be
(a) 50 Ω
(b) 100 Ω
(c) 200 Ω
(c) 400 Ω
A number of resistors are connected as shown in the figure. The equivalent resistance between A and B is
(a) 6 Ω
(b) 12 Ω
(c) 9 Ω
(d) 15 Ω
For the circuit shown, a shorting wire of negligible resistance is added to the circuit between points A and B. When this shorting wire is added, bulb 3 goes out. Which bulbs (all identical) in the circuit are brighten?
(a) Only bulb 2
(b) Only bulb 4
(c) Bulbs 1 and 4
(d) Bulbs 2 and 4
Three infinite planes have a uniform surface charge distribution o on its surface. All charges are fixed. On each of the three infinite planes, parallel to the yz-plane placed at x = – a, x = 0, and x = a, there is a uniform surface charge of the same density σ. The potential difference between A and C is
In the given arrangement of capacitors, 6 μF charge is added to point a. Find the charge on upper capacitor
(a) 3 μC
(b) 1 μC
(c) 2 μC
(d) 6 μC
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