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. Edwin Howard Armstrong was an inventor of which of the following technologies?
[A] Television
[B] Compact Discs
[C] FM Radio
[D] Broadband
Show Answer
Correct Answer: C [FM Radio]
Notes:
Edwin Howard Armstrong was an American electrical engineer who developed FM radio and the superheterodyne receiver system. Edwin Howard Armstrong is the “father of FM radio” and was born in 1890.
3. Crystals of which of the following naturally-occuring substance exhibits both ‘pyroelectric’ and ‘piezoelectric’ properties making it versatile for application in the field of electronics?
[A] Quartz
[B] Mica
[C] Topaz
[D] grapite
Show Answer
Correct Answer: A [Quartz]
Notes:
Quartz crystals have piezoelectric properties: they develop an electric potential upon the application of mechanical stress. An early use of this property of quartz crystals was in phonograph pickups. A common piezoelectric use of quartz today is as a crystal oscillator. The quartz clock is a familiar device using the mineral. Quartz is also strongly pyroelectric. Temperature changes create positive and negative charges within the crystal.
4. In recent times, the “dynamic brake system” is becoming popular in modern railways. The dynamic brake system coverts Kinetic energy to__:
[A] Potential energy
[B] Electricity
[C] Sound energy
[D] Magnetic energy
Show Answer
Correct Answer: B [ Electricity]
Notes:
Modern engines also have, additionally, dynamic brake system which works on the principle of converting kinetic energy of the moving train to electricity making the electric motors to work as generators.
5. Joule/kg is the S.I unit of which of these physical quantities?
[A] Entropy
[B] Permittivity of free space
[C] Latent heat
[D] Gas constant
Show Answer
Correct Answer: C [ Latent heat ]
Notes:
Joule/kg is the S.I unit of Latent heat Latent heat(L) = heat(Q)/mass(m) Latent heat is the heat required to convert a solid into a liquid or vapor, or a liquid into a vapor, without any change in temperature. Unit of Entropy: J/K Unit of Permittivity of free space: H/m Unit of Gas constant : J/K
6. The inablity of a body to change its state of rest or motion is known as:
[A] Force
[B] Momentum
[C] Displacement
[D] Inertia
Show Answer
Correct Answer: D [Inertia]
Notes:
Inertia is the property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force. There are three types of Inertia: 1. Inertia of rest 2. Inertia of motion 3. Inertia of direction
7. What is Young’s Modulus?
[A] ratio of longitudinal strain to normal stress
[B] product of normal stress of longitudinal strain
[C] ratio of normal stress to longitudinal strain
[D] ratio of normal stress to lateral strain
Show Answer
Correct Answer: C [ratio of normal stress to longitudinal strain]
Notes:
Young’s Modulus is defined as the ratio of normal stress to longitudinal strain within limit of proportionality. Y = normal stress/longitudinal strain
8. What will happen if a wire of length L is cut into two or more parts?
[A] each part can hold half the weight as full length wire
[B] each part can hold the same weight as full length wire
[C] each part can hold twice the weight as full length wire
[D] None of the above
Show Answer
Correct Answer: B [each part can hold the same weight as full length wire]
Notes:
If a wire of length L is cut into two or more parts, then it’s each part can hold the same weight. Since breaking force is independent of the length of wire.
9. Which of the following electromagnetic waves are produced due to the radioactive decay of the nucleus?
[A] X-rays
[B] Gamma rays
[C] Radio waves
[D] UV rays
Show Answer
Correct Answer: B [Gamma rays]
Notes:
Gamma rays are produced due to the radioactive decay of the nucleus. Gamma rays have wavelength less than 10–3 nm.
10. What is the wavelength range of ultraviolet rays?
[A] Between 40 nm and 40000 nm
[B] Between 60 nm and 4000 nm
[C] Between 0.0006 nm and 400 nm
[D] Between 0.6 nm and 400 nm
Show Answer
Correct Answer: D [Between 0.6 nm and 400 nm]
Notes:
The ultraviolet rays cover wavelengths ranging from about 4 × 10–7 m (400 nm) down to 6 × 10–10m (0.6 nm). The sun is an important source of ultraviolet light.
