Physics General Knowledge Questions for Competitive Exams
What happens to the force acting between the charged particles, if the distance between these charged particles is halved?
(A) It increases by four times
(B) It gets doubled
(C) It becomes half
(D) It reduces by one-fourth
Correct Answer : A
Explanation :
So, when the distance between the two charges is halved, the force is increased four times.
What is the constant of proportionality of an oscillator if the damping force is directly proportional to the velocity
(A) Kg.s-1
(B) Kg.m.s-1
(C) Kg.s
(D) Kg.m.s-2
Correct Answer : A
Explanation :
The damping force of an oscillating particle is observed to be proportional to velocity. The constant of proportionality can be measured in. kgs−1.
Find the molecular mass of a gas that takes three times more time to effuse as compared to He with the same volume
(A) 9 u
(B) 64 u
(C) 27 u
(D) 36 u
Correct Answer : B
Explanation :
Its molecular mass will be: 64u.
The coefficient performance of a refrigerator is 5. If the temperature inside the freezer is -20℃, calculate the heat rejected to the surrounding
(A) 110C
(B)
410C
(C)
210C
(D)
310C
Correct Answer : A
Explanation :
A heat pump is a heat engine working in reverse direction. A refrigerator is basically a heat pump, which is used to pump heat (absorbed from materials at lower temperatures inside the refrigerator) to the surroundings at higher temperatures. The coefficient of performance of a refrigerator is defined as the ratio of heat removed
Why
2
Energy from inside the refrigerator per cycle
w
given per cycle for heat removal,
α
,
Why
2
,
w
,
Which of the following elements has the largest atomic radii?
(A) Beryllium
(B) Lithium
(C) Nitrogen
(D) Carbon
Correct Answer : B
Explanation :
Francium (Fr) has the highest atomic radius in the periodic table. It belongs to the alkali metals group. Its atomic number is 87. The periodic trend of atomic radius suggests that the atomic radius usually decreases along a period (left to right) and increases down a group (top to bottom).
Bernoulli's theorem is based on?
(A) on energy conservation
(B) on conservation of momentum
(C) on conservation of charge
(D) none of these
Correct Answer : A
Explanation :
Bernoulli's principle is based on the law of conservation of energy. We equate total energy (pressure energy, potential energy and kinetic energy) of a flowing liquid at different points flowing under constant pressure difference.
What is the normal temperature of the human body?
(A) 65 degrees
(B) 95 degree
(C) 98.6°F
(D) 99 degrees
Correct Answer : C
Explanation :
Normal body temperature is considered to be 37°C (98.6°F); however, a wide variation is seen. Among normal individuals, mean daily temperature can differ by 0.5°C (0.9°F), and daily variations can be as much as 0.25 to 0.5°C.
If the electrical resistance is to be reduced, then the number of resistors should be connected with
(A) Mala (Series)
(B) Parallel
(C) Mixed system
(D) None of These
Correct Answer : C
Explanation :
When resistors are connected in parallel, more current flows from the source than would flow for any of them individually, so the total resistance is lower.
What happens to the temperature of water when it falls from a height?
(A) decreases
(B) increases
(C) neither decreases nor increases
(D) none of these
Correct Answer : B
Explanation :
The temperature of water increases when it falls from a height because when a water drop reaches the ground surface from a height, its potential energy increases.
Which of the following is not a unit of heat?
(A) Calorie
(B) Phon
(C) Joule
(D) Kcal
Correct Answer : B
Explanation :
The correct answer is Phon. Phon is not a unit of Heat.
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Rajesh Bhatia
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