Multiple Choice QuestionsA uniform rope of length L and mass m1 hangs vertically from a rigid support. A block of mass m2 is attached to the free end of the rope. A transverse pulse of wavelength 
is produced at the lower end of the rope. The wavelength of the pulse when it reaches the top of the rope is 
. The ratio 
is,
A.
Wavelength of the transverse pulse is,
... (i);
where v is the velocity of the wave and f is the frequency of the wave.
We know that,
T is the tension in the spring
is the mass per unit length of the rope
From eqns. (i) and (ii), we have
For two different cases, we have
A refrigerator works between 4o C and 30o C. It is required to remove 600 calories of heat every second in order to keep the temperature of the refrigerated space constant. The power required is (Take 1 cal = 4.2 Joules)
23.65 W
236.5 W
2365 W
2365 W
A capacitor of 2
is charged as shown in the figure. When the switch s is turned to position 2, the percentage of its stored energy dissipated is,
20%
75%
80%
80%
a potentiometer wire is 100 cm long and a constant potential difference is maintained across it. Two cells are connected in series first to support one another and then in opposite direction. The balance points are obtained at 50 cm and 10 cm from the positive end of the wire in the two cases. The ratio of emf is,
5:4
3:4
3:2
3:2
A long solenoid has 1000 turns. when a current of 4 A flows through it, the magnetic flux linked with each turn of the solenoid is 4x10-3 Wb. The self inductance of the solenoid is,
3H
2H
1H
1H
The magnetic susceptibility is negative for,
a paramagnetic material only
ferromagnetic material only
paramagnetic and ferromagnetic materials
paramagnetic and ferromagnetic materials
A square loop of ABCD carrying a current i, is placed near and coplanar with a long straight conductor XY carrying a current I, the net force on the loop will be
A long straight wire of radius a carries a steady current I. The current is uniformly distributed over its cross-section. The ratio of the magnetic fields B and B' at radial distances 
and 2a respectively, from the axis of the wire is,
1
4
4
A small signal voltage V(t) = Vo sin 
is applied across an ideal capacitor C:
over a full cycle the capacitor C does not consume any energy from the voltage source
current I(t) is in phase with voltage V(t)
Current I(t) leads voltage V(t) by 180o
Current I(t) leads voltage V(t) by 180o
An inductor of 20 mH, a capacitor of 50 
and a resistor of 40 ohm are connected in series across a source of emf V = 10 sin 340 t. the power loss in the ac circuit is,
0.67 W
0.76 W
0.89 W
0.89 W
Switch
