Multiple Choice QuestionsThe amount of heat energy required raising the temperature of 1g of helium at NTP, from T1K and T2K is
3/8 NaKB(T2-T1)
3/2 NaKB(T2-T1)
3/4 NaKB(T2-T1)
3/4 NaKB(T2-T1)
The coefficient of performance of a refrigerator is 5. If the temperature inside freezer is -20o C, th temperature of the surroundings to which it rejects heat is
31o C
41o C
11o C
11o C
The value of the coefficient of volume expansion of glycerin is 5 x 10-4 K-1. The fractional change in the density of glycerin for a rise of 400C in its temperature is
0.015
0.020
0.025
0.025
A cylindrical metallic rod in thermal contact with two reservoirs of heat at its two ends conducts an amount of heat Q in time t. The metallic rod is melted and the material is formed into a rod of half the radius of the original rod. What is the amount of heat conducted by the new rod when placed in thermal contact with the two reservoirs in time t?
Q/4
Q/16
2Q
2Q
If Cp- Cv denote the specific heats (per unit mass) of an ideal gas of molecular weight M
Here R is the molar gas constant
Cp-CV = R/M2
Cp-CV = R
Cp-CV = R/M
Cp-CV = R/M
A block body t 227o C radiates heat at the rate of 7 cal cm-2 s-1. At a temperature of 727o C, the rate of heat radiated in the same units will be
60
50
112
112
On a new scale of temperature (which is linear), an called the W scale, the freezing and boiling point of water are 39o W and 239o W respectively. what will be the temperature of 39o C celsius scale?
78o W
117o C
200o C
200o C
An electric kettle takes 4 A current at 220 V. How much time will it take to boil 1 kg of water from temperature 200 C? The temperature boiling water is 100o C.
6.3 min
8.4 min
12.6 min
12.6 min
If the cold junction of a thermocouple is kept at 0o C and the hot junction is kept at To C, then the relation between neutral temperature (Tn) and temperature of inversion (Ti) is:
Tn = 2Ti
Tn = Ti -T
Tn = Ti -T
Nickel shows the ferromagnetic property at room temperature. If the temperature is increased beyond Curie temperature, then it will show:
paramagnetism
anti -ferromagnetism
no magnetic property
no magnetic property
A.
paramagnetism
Nickel exhibits ferromagnetism because of a quantum physical effect called exchange couplingin which the electron spins of one atom interact with those of neighbouring atoms. The result is aligment of the magentic dipole moments of the atoms, inspite of the randomizing tendency of atomic collisions. The presistent aligment is what gives ferromagnetic material their permanent magnetism.
If the temerature of ferromagnetic material is raised above a certain critical value, called the Curie temperature, the exchange coupling ceases to be effective. Most such material then become simply tend to align with an external field but much more weakly, and thermal agitation can now more easily distrupt the alignmet.
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