Jamb 2021 Physics Past Questions And Answers
I. A liquid boils when its saturated vapor pressure is equal to the external pressure II. Dissolved substances in pure water lead to an increase in the boiling point. III. When the external pressure is increased, the boiling point increases. IV. Dissolved substances in pure water decreases the boiling point Which of the above combinations are peculiarities of the boiling point of a liquid?
- A. I, II and III only
- B. I, II, III, and IV
- C. I, II, and IV
- D. II, III, and IV
An astronomical telescope is said to be in normal adjustment when the?
- A. eye is accommodated
- B. focal length of an object lens is longer than that of eye piece
- C. final image is at the near point of eye
- D. final image is at infinity
The temperature gradient across a copper rod of thickness 0.02m, maintained at two temperature junctions of 20º and 80ºC respectively is?
- A. 3.0 x 102km-1
- B. 3.0 x 103km-1
- C. 5.0 x 103km-1
- D. 3.0 x 104km-1
A man stands 4m in front of a plane mirror. If the mirror is moved 1m towards the man, the distance between him and his new image is?
- A. 3m
- B. 5m
- C. 6m
- D. 10m
A given mass of gas has a pressure of 80 Nm−2 at a temperature of 47oC. If the temperature is reduced to 27oC with volume remaining constant, the new pressure is?
- A. 46.0 Nm−2
- B. 75.0 Nm−2
- C. 80.0 Nm−2
- D. 85.3 Nm−2
Calculate the mass of ice that would melt when 2kg of copper is quickly transferred from boiling water to a block of ice without heat loss (specific heat capacity of copper = 400Jkg\(^{1}\)k\(^{-1}\), latent heat of fusion of ice = 3.3 x 10\(^{5}\)Jkg\(^{-1}\))
- A. \(\frac{8}{33}\)kg
- B. \(\frac{3.3}{80}\)kg
- C. \(\frac{80}{33}\)kg
- D. \(\frac{3.3}{8}\)kg
A man will exert the greatest pressure when he?
- A. lies flat on his back
- B. lies on his belly
- C. stands on both feet
- D. stands on the toes of one foot
If a sound wave goes from a cold air region to a hot air region, its wavelength will?
- A. increase
- B. decrease
- C. decrease then increase
- D. remain constant
If the stress on a wire is 107NM−2 and the wire is stretched from its original length of 10.00 cm to 10.05 cm. The young's modulus of the wire is?
- A. 5.0 x 10−4Nm−2
- B. 5.0 x 10−5Nm−2
- C. 2.0 x 10−8Nm−2
- D. 2.0 x 109Nm−2
A 2H inductor has negligible resistance and is connected to a \(\frac{50}{\pi}\) Hz A.C supply. The reactance of the inductor is?
- A. 200\(\Omega\)
- B. 50\(\Omega\)
- C. \(\frac{100}{\pi}\)
- D. \(\frac{25}{\pi \Omega}\)