A current of \(5\) A is passing through a metallic wire of cross-sectional area \(4\times10^{-6}\) m2. If the density of charge carriers of the wire is \(5\times10^{26}\) m-3, then the drift velocity of the electrons will be:
1. \(1\times 10^2\) m/s
2. \(1.56 \times10^{-2}\) m/s
3. \(1.56 \times10^{-3}\) m/s
4. \(1\times 10^{-2}\) m/s
The numerical ratio of displacement to the distance covered is always:
1. | less than one |
2. | equal to one |
3. | equal to or less than one |
4. | equal to or greater than one |
The principle of LASER action involves:
1. | amplification of particular frequency emitted by the system |
2. | population inversion |
3. | stimulated emission |
4. | all of the above |
A train is moving towards the east and a car is along the north, both at the same speed. The observed direction of the car to the passenger and the train is:
1. east-north direction
2. west-north direction
3. south-east direction
4. none of the above
Which of the following is a unipolar transistor?
1. p-n-p transistor
2. n-p-n transistor
3. field effect transistor
4. point contact transistor
A solid sphere and a hollow sphere of the same material and of the same size can be distinguished without weighing:
1. | by determining their moments of inertia about their coaxial axes |
2. | by rolling them simultaneously on an inclined plane |
3. | by rotating them about a common axis of rotation |
4. | by applying equal torque on them |
Point masses \(1,\) \(2,\) \(3\) and \(4\) kg are lying at the points \((0,0,0),\) \((2,0,0),\) \((0,3,0)\) and \((-2,-2,0)\) respectively. The moment of inertia of this system about the X-axis will be:
1. \(43~\mathrm{kg-m^2}\)
2. \(34~\mathrm{kg-m^2}\)
3. \(27~\mathrm{kg-m^2}\)
4. \(72~\mathrm{kg-m^2}\)
The radius of gyration of a body about an axis at a distance \(6~\mathrm{cm}\) from its centre of mass is \(10~\mathrm{cm}\). Then, its radius of gyration about a parallel axis through its centre of mass will be:
1. \(80~\mathrm{cm}\)
2. \(8~\mathrm{cm}\)
3. \(0.8~\mathrm{cm}\)
4. \(80~\mathrm{m}\)
A galvanometer can be changed into an ammeter by using:
1. | low resistance shunt in series |
2. | low resistance shunt in parallel |
3. | high resistance shunt in series |
4. | high resistance shunt in parallel |
A bullet of mass \(20\) g and moving with \(600\) m/s collides with a block of mass \(4\) kg hanging with the string. What is the velocity of a bullet when it comes out of the block, if the block rises to height \(0.2\) m after collision?
1. \(200\) m/s
2. \(150\) m/s
3. \(400\) m/s
4. \(300\) m/s