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.
11. The motion of an object under free fall is an example of which of the following?
[A] uniform velocity
[B] uniform acceleration
[C] zero acceleration
[D] non-uniform acceleration
Show Answer
Correct Answer: B [uniform acceleration]
Notes:
The motion of an object under free fall is a case of uniform acceleration. If an object is released from a height near the surface of earth, it accelerates downwards under the influence of a gravity pull with acceleration due to gravity.
12. The centripetal force and centrifugal force are ______:
[A] equal in magnitude and have same direction
[B] unequal in magnitude and have same direction
[C] equal in magnitude and have opposite direction
[D] unequal in magnitude and have opposite direction
Show Answer
Correct Answer: C [equal in magnitude and have opposite direction]
Notes:
The centripetal force and centrifugal force are equal in magnitude and have opposite direction. Centrifugal force can be regarded as the reaction of centripetal force.
13. What kinds of waves are the ultrasonic waves in air produced by a vibrating quartz crystal?
[A] Transverse
[B] Longitudinal
[C] Transverse and longitudinal
[D] None of the above
Show Answer
Correct Answer: B [Longitudinal]
Notes:
The ultrasonic waves in air produced by a vibrating quartz crystal are longitudinal waves.
14. Which portion of the electromagnetic spectrum can be perceived by the human eye?
[A] Between 400 nm and 700 nm
[B] Between 40 nm and 70 nm
[C] Between 400 nm and 7000 nm
[D] Between 4 nm and 700 nm
Show Answer
Correct Answer: A [Between 400 nm and 700 nm]
Notes:
The human eye is capable of detecting light in the range of approximately 400 nm to 700 nm on the electromagnetic spectrum. This corresponds to the frequency range of about 4 × 10^14 to 7 × 10^14 Hz. This detection range falls within the visible light spectrum. It’s fascinating how our eyes are naturally tuned to this specific range, enabling us to perceive the palette of colors in our surroundings but unable to see ultraviolet or infrared radiation that are just outside this narrow band.
15. Which of the following represents the speed of a sound wave?
[A] wavelength x frequency
[B] 2 x wavelength x frequency
[C] wavelength/frequency
[D] (wavelength x frequency)/2
Show Answer
Correct Answer: A [wavelength x frequency]
Notes:
The speed of sound is defined as the distance which a point on a wave, such as a compression or a rarefaction, travels per unit time. It is represented by s = wavelength x frequency.
16. Which of the following is correct about the rate of loss of heat of the body, as per the Newton’s law of cooling?
[A] It is directly proportional to the difference of body’s temperature and the surroundings
[B] It is inversely proportional to the difference of body’s temperature and the surroundings
[C] It is equal to the difference of body’s temperature and the surroundings
[D] None of the above
Show Answer
Correct Answer: A [It is directly proportional to the difference of body’s temperature and the surroundings]
Notes:
According to Newton’s law of cooling, the rate of loss of heat, – dQ/dt of the body is directly proportional to the difference of temperature of the body and the surroundings.
17. Which of the following represents the Snell’s law?
[A] sine of angle of incidence/sine of angle of refraction = constant
[B] cosine of angle of incidence/cosine of angle of refraction = constant
[C] tangent of angle of incidence/tangent of angle of refraction = constant
[D] angle of incidence – angle of refraction = constant
Show Answer
Correct Answer: A [sine of angle of incidence/sine of angle of refraction = constant]
Notes:
The ratio of sine of angle of incidence to the sine of angle of refraction is a constant, for the light of a given colour and for the given pair of media. This law is also known as Snell’s law of refraction.
18. What of the following represents linear magnification?
[A] ratio of the height of the image to the height of the object
[B] ratio of the height of the object to the height of the image
[C] product of the height of the object to the height of the image
[D] difference of the height of the image to the height of the object
Show Answer
Correct Answer: A [ratio of the height of the image to the height of the object]
Notes:
The linear magnification (m) is defined as the ratio of the height of the image to the height of the object.
19. What do we call an arrangement of two unlike poles of equal strength separated by a small distance?
[A] Magnetic dipole
[B] Solenoid
[C] Toroid
[D] Electric dipole
Show Answer
Correct Answer: A [Magnetic dipole]
Notes:
Magnetic dipole is an arrangement of two unlike magnetic poles of equal pole strength separated by a very small distance.
20. Which of these rays have the highest ionising power?
[A] Alpha
[B] Beta
[C] Gamma
[D] All have the same
Show Answer
Correct Answer: A [Alpha]
Notes:
Alpha rays have the highest ionising power followed by Beta rays and then Gamma rays.
