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. $\frac{10}{9}A$

Three equal resistances each of value R are joined as shown in the figure. The equivalent resistance between M and N is 

1. R

2. 2R

3. $\frac{R}{2}$

4. $\frac{R}{3}$