Electric Current – Maharashtra Board Class 8 Solutions for General Science (English Medium)
MathematicsGeneral ScienceMaharashtra Board Solutions
Solution 1.a:
The direction of the current in an electric motor is reversed after every half round to keep it working. Otherwise, the North pole of the magnet comes near the South pole of the magnet and causes attraction between them, and the motor stops working.
Solution 1.b:
The strength of an electromagnet can be increased by increasing the number of turns in the coil and increasing current in the coil.
Solution 1.c:
An electric motor works on the principle that when a rectangular coil is placed in a magnetic field and the current is passed through it, a force acts on the coil which rotates it continuously.
Solution 1.d:
A key can open or close the circuit. When the key is closed, the circuit is completed or closed and the current flows through the conducting wires. When the key is open, the circuit is open and the current does not flow through the conducting wires.
Solution 1.e:
Yes. The mechanism of a shirt button is like that of the key in an electric circuit.
If all the buttons of the shirt are closed, then we cannot feel the outside temperature, whereas if the buttons of the shirt are open, then we can feel the outside temperature.
Solution 2.a:
Yes. The mechanism of a shirt button is like that of the key in an electric circuit.
If all the buttons of the shirt are closed, then we cannot feel the outside temperature, whereas if the buttons of the shirt are open, then we can feel the outside temperature.
Solution 2.b:
When the switch is pressed, the circuit gets completed and an electric current flows through the coil. This current attracts the flexible iron strip. The striker then hits the gong and the sound is produced. The contact of the strip with the screw breaks, and the current stops and the coil does not behave as a magnet. The flexible strip moves back and makes contact with the screw. This causes the current to flow again, and the striker again hits the gong.
Solution 2.c:
Electrical switches are made of plastic because plastic is an insulator which does not allow the current to pass through it.
Solution 3:
| ‘A’ | ‘B’ |
| a. Carbon, zinc | 3. Dry cell |
| b. Copper, zinc | 4. Simple cell |
| c. Electric motor | 1. Armature |
| d. Protection from electric current | 2. Insulator |
Solution 4:
