Question

A wire is connected to a battery between the points M and N as shown in figure 
(1). The same wire is bent in the form of a square and then connected to the battery between the points M and N as shown in figure 
(2). Which of the following quantities increases? 

• A. Heat produced in the wire and resistance offered by the wire
• B. Resistance offered by the wire and current through the wire
• C. Heat produced in the wire, resistance offered by the wire and current through the wire
• D. Heat produced in the wire and current through the wire

Hint:

Resistance of a wire is independent of its shape. Heat produced increases if current increases.

Answer 1

The Correct Option is D

Step 1: Resistance of a wire depends only on its material, length and cross-sectional area: R = ρ (L)/(A) Bending the wire does not change its resistance.

 Step 2: When the wire is bent into a square and connected across the same battery, the effective distance between terminals is reduced, leading to increased current due to lower potential drop per unit length. 

Step 3: Since current increases and resistance remains constant, heat produced: H = I²Rt also increases.