Three copper wires have their lengths in the ratio 5:3:1 and their masses are in the ratio 1:3:5. Their electrical resistance will be in the ratio of :

1. 5:3:1

2. 1:3:5

3. 125:15:1

4. 1:15:125

The current \(I\) as shown in the circuit will be:

When the length and area of cross-section both are doubled, then its resistance :

(1) Will become half

(2) Will be doubled

(3) Will remain the same

(4) Will become four times

An electric wire of length ‘I’ and area of cross-section a has a resistance R ohms. Another wire of the same material having the same length and area of cross-section 4a has a resistance of :

(1) 4R

(2) R/4

(3) R/16

(4) 16R

A wire of radius r has resistance R. If it is stretched to a radius of $\frac{3r}{4}$, its resistance becomes 

(1) $\frac{9R}{16}$

(2) $\frac{16R}{9}$

(3) $\frac{81R}{256}$

(4) $\frac{256R}{81}$

Express which of the following setups can be used to verify Ohm’s law 

(1)
(2)
(3)
(4)

What is the resistance of a carbon resistance which has bands of colours brown, black and brown 

(1) 100 Ω

(2) 1000 Ω

(3) 10 Ω

(4) 1 Ω

The following four wires are made of the same material and are at the same temperature. Which one of them has highest electrical resistance :

(1) Length = 50 cm, diameter = 0.5 mm

(2) Length = 100 cm, diameter = 1 mm

(3) Length = 200 cm, diameter = 2 mm

(4) Length = 300 cm, diameter = 3 mm