AL MC x5

1. The forward bias is the voltage across the diode when it is conducting. Hence, the ouptput voltage across the resistor R is smaller than the voltage supplied by the source.
The answer is option B

2. Option D is correct.

3. Magnetic field at D is mostly given by solenoid X
The magnetic flux density B = (4 x pi x 10^-7) x 1200 x 1 T
= 1.5 x 10^-3 T = 1.5 mT

4. Light rays propagate through the glass tube fibre by repeated total internal reflection at critical angle on the inner surface of the tube. In this way, the rays would take the longest time of travel through the entire tube.
The shortest time is for light rays to travel straight through the tube.
The answer is option C

5. At speed v, there is no radial friction acting on the vehicle, as the radial component of the normal reaction is sufficient to provide for the necessary centripetal force.
Therefore, at higher speeds, the weight component of normal reaction is no longer be large enough to provide the increased centripetal force. Radial friction needs to come into play.
Also, the normal reaction at the tyres on the outside of the vehicle must be larger than that at the inside tyres in order to maintain an equilibrium about the centre of mass of the vehicle.
[Try to take moment about the centre of mass of the vehicle, only the moment from the normal reaction at the tyres on the outside is anticlockwise, the other forces (moments) are clockwise. Thus the normal reaction at the tyres on the outside needs to be larger than that on the inside tyres.]