For the circuit shown in the figure, the current \(I\) will be:

              

1. \(0.75~\text{A}\)
2. \(1~\text{A}\) 
3. \(1.5~\text{A}\)
4. \(0.5~\text{A}\)

Two batteries, one of emf \(18\) volts and internal resistance \(2~\Omega\) and the other of emf \(12\) V and internal resistance \(1~\Omega,\) are connected as shown. The voltmeter \(\mathrm{V}\) will record a reading of: 

1. \(18\) V
2. \(30\) V
3. \(14\) V
4. \(15\) V

As the temperature of a metallic resistor is increased, the product of its resistivity and conductivity:

When no current is passed through a conductor,

Choose the correct option: 
1. (a) only 
2. (b), (c) 
3. (c), (d) 
4. (a), (d) 

A charged particle having drift velocity of \(7.5\times10^{-4}~\text{ms}^{-1}\) in an electric field of \(3\times10^{-10}~\text{Vm}^{-1}\), has mobility of: 
1. \(2.5\times 10^{6}~\text{m}^2\text{V}^{-1}\text{s}^{-1}\)
2. \(2.5\times 10^{-6}~\text{m}^2\text{V}^{-1}\text{s}^{-1}\)
3. \(2.25\times 10^{-15}~\text{m}^2\text{V}^{-1}\text{s}^{-1}\)
4. \(2.25\times 10^{15}~\text{m}^2\text{V}^{-1}\text{s}^{-1}\)