Carnot engine having an efficiency of 1/10 as heat engine, is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is
1 J
90 J
99 J
99 J
The bulk modulus of a spherical object is ‘B’. If it is subjected to uniform pressure ‘p’, the fractional decrease in radius is
p/B
B/2p
3p/B
3p/B
D.
3p/B
A spherical black body with a radius of 12 cm radiates 450-watt power at 500 K. If the radius were halved and the temperature doubled, the power
radiated in watt would be
225
450
1800
1800
Two blocks A and B of masses 3m and m respectively are connected by a massless and inextensible string. The whole system is suspended by a massless spring as shown in the figure. The magnitudes of acceleration of A and B immediately after the string is cut, are respectively
g,g/3
g/3, g
g,g
g,g
A rope is wound around a hollow cylinder of mass 3 kg and radius 40 cm. What is the angular acceleration of the cylinder if the rope is pulled with a force of 30 N?
25 m/s2
0.25 rad/s2
25 rad/s2
25 rad/s2
The two nearest harmonics of a tube closed at one end and open at other end are 220 Hz and 260 Hz. What is the fundamental frequency of the system?
10 Hz
20 Hz
30 Hz
30 Hz
A potentiometer is an accurate and versatile device to make electrical measurements of E.M.F, because the method involves :
Cells
Potential gradients
A condition of no current flow through the galvanometer
A condition of no current flow through the galvanometer
A 250-Turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of 85 μA and subjected to a magnetic field of strength 0.85 T. Work done for rotating the coil by 180° against the torque is
9.1 μJ
4.55 μJ
2.3 μJ
2.3 μJ
Figure shows a circuit contains three identical resistors with resistance R = 9.0 Ω each, two identical inductors with inductance L = 2.0 mH each, and an ideal battery with emf ε= 18 V. The current'i' through the battery just after the switch closed is
2 mA
0 mA
2 A
2 A
A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of resulting system
Increases by a factor of 4
Decreases by a factor of 2
Increases by a factor of 2
Increases by a factor of 2