A Carnot engine, having an efficiency of η = 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
99 J
90 J
1 J
1 J
One end of a thermally insulated rod is kept at a temperature T1 and the other at T2. The rod is composed of two sections of lengths
(k2
(k2
(k1
(k1
If Cp and Cv denote the specific heats of nitrogen per unit mass at constant pressure and constant volume respectively, then
Cp – Cv = R/28
Cp −Cv = R/14
Cp −Cv = R
Cp −Cv = R
A.
Cp – Cv = R/28
A charged particle moves through a magnetic field perpendicular to its direction. Then
the momentum changes but the kinetic energy is constant
both momentum and kinetic energy of the particle are not constant
both, momentum and kinetic energy of the particle are constant
both, momentum and kinetic energy of the particle are constant
Two springs, of force constants k1 and k2, are connected to a mass m as shown. The frequency of oscillation of the mass is f. If both k1 and k2 are made four times their original values, the frequency of oscillation becomes
f/2
f/4
4f
4f
When a system is taken from state i to state f along the path iaf, it is found that Q = 50 cal and W = 20 cal. Along the path’ ibf Q = 36 cal. W along the path ibf is
6 cal
66 cal
16 cal
16 cal
A particle of mass m executes simple harmonic motion with amplitude ‘a’ and frequency ‘ν’. The average kinetic energy during its motion from the position of equilibrium to the end is
π2m a2 v2
ma2 v2/4
4π2ma2v2
4π2ma2v2
In an a.c. circuit the voltage applied is E = E0 sinπt. The resulting current in the circuit is I = I0 sin .The power consumption in the circuit is given by
P = zero
An electric charge 10-3 µC is placed at the origin (0,0) of X - Y coordinate system. Two points A and B are situated at and (2, 0) respectively. The potential difference between the points A and B will be
9 volt
0 volt
2 volt
2 volt
A battery is used to charge a parallel plate capacitor till the potential difference between the plates becomes equal to the electromotive force of the battery. The ratio of the energy stored in the capacitor and the work done by the battery will be
1
2
1/4
1/4