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 among the following radiations in the Sunlight causes tanning and sunburn?
[A] Ultraviolet
[B] Visible
[C] Infrared
[D] Micro waves
Show Answer
Correct Answer: A [Ultraviolet]
Notes:
The sunlight that reaches the earth has ultraviolet A and ultraviolet B (UVA and UVB) rays. These ultraviolet rays are the main causes of damage to the skin from the sun. UVA and UVB rays affect the skin’s sensitivity to sun exposure in different ways.
2. A pendulum is taken to Moon, what will happen to its time period?
[A] Increases
[B] Decreases
[C] Remains constant
[D] Either increase or decrease
Show Answer
Correct Answer: A [Increases]
Notes:
When the simple pendulum is taken to the moon, value of gravitational constant g will decrease and thus, its time period will increase.
3. Mach number is a measure of which of the following?
[A] Speed
[B] Heat Transfer
[C] Static Pressure
[D] Volume
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Correct Answer: A [Speed]
Notes:
Mach number refers to the ratio of the velocity of a fluid to the velocity of sound in that fluid, named after Ernst Mach (1838–1916), an Austrian physicist and philosopher. Speed of sound is Mach 1 speed.
4. Which among the following is measured by an Odometer?
[A] Pressure
[B] Height
[C] Distance
[D] Velocity
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Correct Answer: C [Distance]
Notes:
An odometer is an instrument used for measuring the distance. It measures distance traveled by a vehicle such as a bicycle or car. The device may be electronic, mechanical, or a combination of the two.
5. If the distance between the earth and the sun becomes one-fourth of what it is now, the gravitational force exerted on the earth by the sun would be:
[A] One-fourth of what it is now
[B] One-sixteenth of what it is now
[C] Sixteen times of what it is now
[D] Four times of what it is now
Show Answer
Correct Answer: C [ Sixteen times of what it is now]
Notes:
Gravitational force is inversely proportional to the square of the distance between the bodies.
6. Nuclear Reactors are based on which of the following phenomenon?
[A] Magnetic confinement of Plasma
[B] Nuclear Fusion
[C] Controlled Nuclear Fission
[D] None of the above
Show Answer
Correct Answer: C [Controlled Nuclear Fission]
Notes:
Nuclear Reactors uses Controlled Nuclear Fission to generate electricity. A nuclear reactor splits the atoms of nuclear fuel (eg. uranium) to generate energy to turn water into steam to drive turbine generators. Nuclear fission is the splitting of a heavy nucleus into two lighter ones. Fission was discovered in 1938 by the German scientists Otto Hahn, Lise Meitner, and Fritz Strassmann.
7. What is the S.I. unit for Luminous Intensity?
[A] mole
[B] ampere
[C] candela
[D] weber
Show Answer
Correct Answer: C [ candela ]
Notes:
The S.I. unit for Luminous Intensity is candela. The symbol used for candela is cd. Mole is the S.I unit for Quantity of Matter ampere is the S.I unit for Electric Current. Weber is the S.I unit for Magnetic Flux Luminous Intensity is the amount of light that a point source radiates in a given direction
8. Which of the following physical quantities has no units?
[A] Reynold Number
[B] Rydberg constant
[C] Wave number
[D] Hubble constant
Show Answer
Correct Answer: A [ Reynold Number ]
Notes:Reynold Number has no units. The Reynolds number is the ratio of inertial forces to viscous forces. It is used for predicting if a flow condition will be laminar or turbulent.
- Unit of Rydberg constant: m-1
- Unit of Wave number = m-1
- Unit of Hubble constant = sec-1
9. Which of the following is correct about Kinetic energy during the projectile motion?
[A] it is minimum at the point of projection
[B] it is minimum at the highest point
[C] it is maximum at the highest point
[D] it is minimum at the point of reaching the ground
Show Answer
Correct Answer: B [it is minimum at the highest point]
Notes:
The Kinetic energy of an object is maximum at the point of projection or at the point of reaching the ground. It is minimum at the highest point.
10. 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
