Physics objective test for Exams

Physics objective test for Exams
Physics Objective Questions And Answers Free
Physics - Online Multiple Choice

1. In a germanium semiconductor material used in transistors, mobility of electrons is 3900 cm2/V How much velocity do they have?
(a) 3900 m/s
(b) 7800 m/s
(c) 1000 m/s
(d) 4000 m/s
Ans. (a)

2. Curie temperature of. Iron is that temperature below which it is : -
(a) Ferromagnetic
(b) Electrically conducting
(c) Superconducting
(d) Radioactive
Ans. (a)


3. In radio reception, the strength of the received signal varies and to provide a constant output power, it is necessary to vary the gain power, it is necessary to vary the gain of the receiver. This is usually done by:
(a) a diode
(b) a pentode
(c) n-p-n transistor
(d) Automatic volume control
Ans. (b)

4. An electric charge is surrounded by several other electric charges. The force exerted by one of the surrounding charges on this charge:
(a) Decreases because of the other charges
(b) Increases because of the surrounding charges
(c) Is independent of the presence of other charges
(d) Depends on the position of other charges
Ans. (c)

5. Which one of the following pairs is NOT correctly matched?
(a) Pion — Meson
(b) Proton — Baryon
(c) Neutrins — Lepton
(d) Lambda — Meson
Ans. (d)

6. Which of the following factors do not affect the frequency stability of an oscillator?
(a) Output load
(b) Inter-element capacitances and stray capacitances
(c) Temperature variation
(d) Coil size
Ans. (a)

7. Which one of the following is a set of magic numbers?
(a) 1, 2, 8, 16, 20, 28
(b) 2, 8, 16, 20, 28, 50
(c) 8, 28, 50, 82, 100, 126
(d) 2, 8, 20, 28, 50, 82, 126
Ans. (d)

8. Carbon dioxide shows a Raman line at 1080 cm-1. Consider the, following statements in this regard:
1. The corresponding infrared absorption will be found at 1080 cm-1.
2. The corresponding infrared absorption band will be absent.
3. CO2 is a linear and symmetric molecule.
Of these statements:
(a) 1 and 3 are correct
(b) 2 and 3 are correct
(c) 2 alone is correct
(d) 3 alone is correct
Ans. (a)

9. The average binding energy per nucleon is 7.6 MeV for a heavy nucleus such as uranium while it is 8.5 MeV for nuclei with mass numbers around 110. The energy released. in binary fission of U—235 by slow neutrons will be approximately:
(a) 7.6 MeV
(b) 8.5 MeV
(c) 212.4 MeV
(d) 235 MeV
Ans. (c)

10. In a prism, the dispersion is related to the wavelength λ as
(a) λ-1
(b) λ-2
(c) λ-3
(d) λ-4
Ans. (c)

11. A light ray travels through media A and B having refractive indices of 4/3 and 3/2 respectively. If the thickness of the medium A is 4 cm and that of B is 6 cm, then the optical path length in the combined media will be:
(a) 7/3
(b) 12/3
(c) 37/3
(d) 43/3
Ans. (d)

12. When excited by a light of wavelength 4358 Å, a transparent substance produces a Stokes Raman frequency shift of 458 cm-1. The wavelength of the antistokes line is:
(a) 4058 Å
(b) 4274 Å
(c) 4448 Å
(d) 4548 Å
Ans. (b)

13. An ultrasonic sound pulse is sent vertically down the ocean waters and the echo is received 3 s later. The depth of the ocean at that place is approximately:
(a) 1.1 kin
(b) 2.2 km
(c) 3.3 km
(d) 4.4 km
Ans. (b)


14. When two tuning forks A and B are sounded together 6 beats/s are produced. The frequency of B is 320 Hz. If some wax is added to A and again sounded with B, again 6 beats/s are produced. The frequency of A is:
(a) 326 Hz
(b) 332 Hz
(c) 314 Hz
(d) 308 Hz
Ans. (a)

15. Two railway engines removing on parallel tracks in opposite direction, each with a speed of 72 km/h. The whistle of one engine blows a note of frequency 589 Hz. Given that the velocity of sound is 330 m/s, the frequency which will be heard by the driver of the other engine, just before crossing is
(a) 919 Hz
(b) 665 Hz
(c) 589 Hz
(d) 259 Hz
Ans. (b)

16. A thermos bottle containing coffee is vigorously shaken. If the coffee is considered as a system, then the temperature of the coffee will
(a) Increase slightly
(b) Fall
(c) Remain the same
(d) Never be determined
Ans. (a)

17. An open organ pipe has a fundamental frequency of 300 Hz. The first overtone of this organ pipe is the same as the first overtone of a closed organ pipe. The length of the closed organ pipe is (assume velocity of sound in air as330m/s):
(a) 0.41m
(b) 0.78m
(c) 0.82m
(d) 0.90m
Ans. (a)

18. Steam at 100°C causes more severe burns than water at the same temperature
Because
(a) Steam is a gas
(b) Steam cannot do work
(c) Steam can provide more heat
(d) Steam is highly combustible
Ans. (c)

19. A container having some gas was kept in a moving train. The temperature of the
gas in the container will
(a) Increase slightly
(b) Decrease
(c) Remain the same
(d) Become infinite
Ans. (a)

20. Two glass tumblers have been stuck together (one into the other). They can be
Separated by
(a) placing hot water in the inner tumbler
(b) placing the tumblers in cold water
(c) placing the outer tumbler in hot water
(d) hammering them vigorously
Ans. (c)

21. A test tube containing some water is surrounded by melting ice (pure). Then,
the water in the test tube will
(a) not freeze into ice
(b) freeze into ice
(c) boil ultimately
(d) become steam ultimately
Ans. (a)

22. Heat flows as a result of difference
(a) temperature
(b) weight
(c) mass
(d) none of these
Ans. (a)

23. The quantity of heat required to raise the temperature of 2000 g of water from
10°C to 50°C is
(a) 80 cal
(b) 30,000 cal
(c) 8000 cal
(d) none of these
Ans. (b)

24. The unit of thermal capacity is
(a) cal/°C
(b) cal/g
(c) cal/g/°C
(d) none of these
Ans. (a)


25. If the thermal capacity of a body is infinity, then
(a) Heat can never be added to it
(b) Heat can never be extracted from it
(c) The temperature of the body cannot be altered by adding or extracting any
amount of heat
(d) It has infinite amount of heat
Ans. (c)