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

The current in the adjoining circuit will be 

(1) $\frac{1}{45}ampere$

(2) $\frac{1}{15}ampere$

(3) $\frac{1}{10}ampere$

(4) $\frac{1}{5}ampere$

The reading of the ammeter as per figure shown is

(1) $\frac{1}{8}A$

(2) $\frac{3}{4}A$

(3) $\frac{1}{2}A$

(4) 2 A

A current of 2 A flows in a system of conductors as shown. The potential difference $(V_A-V_B)$ will be 

(1) +2 V

(2) +1 V

(3) –1 V

(4) –2 V

Four resistances are connected in a circuit in the given figure. The electric current flowing through 4 ohm and 6 ohm resistance is respectively 

(1) 2 amp and 4 amp

(2) 1 amp and 2 amp

(3) 1 amp and 1 amp

(4) 2 amp and 2 amp

In the given figure, when key K is opened, the reading of the ammeter A will be

(1) 50 A

(2) 2 A

(3) 0.5 A

(4) $\frac{10}{9}A$