Physics MCQs
Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, NDA, CDS and all one day examinations of India.
1. Which eye defect causes image focus in front of the retina?
[A] Presbyopia
[B] Hypertropia
[C] Myopia
[D] Hyperopia
Show Answer
Correct Answer: C [Myopia]
Notes:
Myopia (short-sightedness) occurs when images are focused in front of the retina, causing distant objects to appear blurry. It is commonly due to an elongated eyeball or excessive corneal curvature. This defect is corrected using concave (diverging) lenses. Hyperopia, by contrast, focuses images behind the retina.
2. Ohm is a unit of measuring _________?
[A] Resistance
[B] Voltage
[C] Current
[D] None of the above
Show Answer
Correct Answer: A [Resistance]
Notes:
The ohm is the SI unit of electrical resistance. Electrical resistance of an object is the measure of its obstruction to the flow of electric current. It mainly depends on the material it is made of, cross sectional area of a conductor, length and temperature. The resistance of a conductor of unit cross-sectional area and unit length is known as Resistivity. The unit of resistivity is ohm-metre.
3. A small quantity of water is placed in a small cavity made in a block of Ice at 0 degree centigrade. Which of the following will happen?
[A] the temperature of water will become zero and it will freeze
[B] the temperature of water will become zero but it will not freeze
[C] the temperature of the water will become zero and it will come out of the cavity
[D] the temperature of the water will become zero and ice will melt to merge with water
Show Answer
Correct Answer: B [the temperature of water will become zero but it will not freeze]
Notes:
When a small quantity of water is placed in a small cavity made in a block of Ice at 0 degree centigrade the temperature of water will become zero but it will not freeze.
4. With reference to a swinging pendulum, which among the following statements is correct when it is at bottom (middle of arc)?
[A] It has maximum kinetic energy and minimum potential energy
[B] It has maximum potential energy and minimum kinetic energy
[C] It has zero kinetic energy
[D] It has zero total energy
Show Answer
Correct Answer: A [ It has maximum kinetic energy and minimum potential energy]
Notes:
At the lowest point of its motion of swinging pendulum, kinetic energy is maximum and gravitational potential energy is minimum. At the highest point of its motion, kinetic energy is minimum and gravitational potential energy is maximum.
5. Which of these is the cause of Friction?
[A] Roughness of surfaces in contact
[B] Force of adhesion between the molecules of the surfaces in contact
[C] Both a and b
[D] None of the above
Show Answer
Correct Answer: C [Both a and b]
Notes:
Friction is the force that opposes the relative motion between the two surfaces of objects in contact. Friction is caused due to: 1. Roughness of surfaces in contact 2. Force of adhesion between the molecules of the surfaces in contact
6. Which of the following is NOT correct about the velocity of rocket at any time?
[A] it is directly proportional to the exhaust speed of the gases
[B] it is directly proportional to the natural log of ratio of intial mass of rocket to its mass at that instant
[C] length of the rocket
[D] All of the above
Show Answer
Correct Answer: C [length of the rocket]
Notes:
The velocity of rocket at any time is directly proportional to the exhaust speed of the gases and to the natural log of ratio of intial mass of rocket to its mass at that instant. V = u log(m1/m2)
7. The work done by a variable force is given by:
[A] area under the force curve and the displacement axis
[B] square of the area under the force curve and the displacement axis
[C] natural log of the area under the force curve and the displacement axis
[D] twice the area under the force curve and the displacement axis
Show Answer
Correct Answer: A [area under the force curve and the displacement axis]
Notes:
The work done by a variable force is given by the area under the force curve and the displacement axis. W = Area ABCDA
8. Which of the following is true about the effect of altitude on the value of acceleration due to gravity?
[A] The acceleration due to gravity decreases with height
[B] The acceleration due to gravity increases with height
[C] The acceleration due to gravity is not dependent on height
[D] None of the above
Show Answer
Correct Answer: A [The acceleration due to gravity decreases with height]
Notes:
The acceleration due to gravity decreases with height. G0= g(1-2h/R) where h is the height above the surface of the earth.
9. What will be the effect on the value of acceleration due to gravity at the poles if the rate of rotation of earth increases?
[A] No effect
[B] it will increase
[C] it will decrease
[D] it will become zero
Show Answer
Correct Answer: A [No effect]
Notes:
If the rate of rotation of earth increases then the value of acceleration due to gravity decreases at all the places on the surface of earth except at poles.
10. The minimum speed required to put a satellite into a given orbit around earth is known as:
[A] Escape velocity
[B] Orbital velocity
[C] Kinetic velocity
[D] None of the above
Show Answer
Correct Answer: B [Orbital velocity]
Notes:
The minimum speed required to put a satellite into a given orbit around earth is known as Orbital velocity of the satellite. Orbital velocity (v) = (GM/r)1/2 where G= gravitational constant, M= mass of the earth and r = radius of the orbit of the satellite.
