Electricity: Magnetic and Heating Effects

Given: A statement about the Voltaic cell.

Concept: In a Voltaic cell, a conducting liquid (solution) is used through which ions move to complete the circuit and allow chemical reactions to generate electricity.

Answer: The solution used in a Voltaic cell is called electrolyte.

The electrolyte (e.g., lemon juice, salt solution, dilute sulphuric acid) conducts electricity between the two metal electrodes and enables the chemical reactions that produce electric current.

Given: A statement about a current-carrying coil.

Concept: When electric current flows through a coil of wire, it produces a magnetic field around it, giving it properties similar to a bar magnet (with a North pole and a South pole).

Answer: A current carrying coil behaves like a magnet (electromagnet).

It can attract magnetic materials and deflect a magnetic compass needle, just like a bar magnet does.

Answer: False

Justification: Dry cells use a paste-like electrolyte (instead of a liquid), making them compact, leak-proof, and easy to carry. Voltaic cells use liquid electrolytes, which can spill, making them bulkier and less portable. Therefore, dry cells are more portable than Voltaic cells, not less.

Answer: True

Justification: The magnetic effect is produced by the flow of electric current through the coil. When current flows, the coil behaves like a magnet (electromagnet). When the current is switched off, the magnetic effect disappears. Hence, the coil acts as an electromagnet only when current flows through it.

Answer: False

Justification: A battery of 2 cells provides a higher voltage (and hence a larger current) than a single cell. A larger current through the coil produces a stronger magnetic field, which means the electromagnet with 2 cells will attract more iron paper clips than the one with a single cell. So the statement is false.

Answer: (c) Both (i) and (ii) are correct

Justification:

- Statement (i) — True: When electric current flows through a nichrome wire, due to the heating effect of electric current, the wire generates heat and becomes warm. Nichrome has high resistance, so it heats up noticeably.

- Statement (ii) — True: When electric current flows through any conductor (including a nichrome wire), it produces a magnetic field around it (magnetic effect of electric current). This magnetic field deflects the needle of a magnetic compass placed nearby.

Both effects — heating and magnetic — occur simultaneously whenever current flows through a wire. Hence, option (c) is correct.

Given: Four items in Column A to be matched with four descriptions in Column B.

Concept used: Properties and applications of each item.

Matching:

| Column A | | Column B |
|---|---|---|
| (i) Voltaic cell | → | (d) Generates electricity by chemical reactions |
| (ii) Electric iron | → | (c) Works on heating effect of electric current |
| (iii) Nichrome wire | → | (a) Best suited for electric heater |
| (iv) Electromagnet | → | (b) Works on magnetic effect of electric current |

Explanation:
- A Voltaic cell converts chemical energy into electrical energy through chemical reactions.
- An electric iron uses the heating effect of current to heat its base plate for pressing clothes.
- Nichrome wire has high resistance and high melting point, making it best suited as the heating element in electric heaters.
- An electromagnet is based on the magnetic effect of electric current — a current-carrying coil with an iron core acts as a magnet.