Resistance is given by the equation,

R = ρ l/A

where,

ρ is the resistivity of the material of the wire,

l is the length of the wire

A is the area of the cross-section of the wire.

From the equation, it is evident that the area of the cross-section of wire is inversely proportional to the resistance. Therefore, thinner the wire, more the resistance and vice versa. Hence, current flows more easily through a thick wire than a thin wire.

Answered by Shivani Kumari | 2 years ago**Explain the following.**

**a.** Why is the tungsten used almost exclusively for filament of electric lamps?

**b. **Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?

**c.** Why is the series arrangement not used for domestic circuits?

**d.** How does the resistance of a wire vary with its area of cross-section?

**e.** Why copper and aluminum wires are usually employed for electricity transmission?

An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.

Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?

Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to the electric mains supply. What current is drawn from the line if the supply voltage is 220 V?

**Compare the power used in the 2 Ω resistor in each of the following circuits:**

**(i) **a 6 V battery in series with 1 Ω and 2 Ω resistors, and

**(ii)** a 4 V battery in parallel with 12 Ω and 2 Ω resistors.