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. A train travels at the speed of 180 km/hr. What is its speed in m/s?
[A] 5 m/s
[B] 30 m/s
[C] 40 m/s
[D] 50 m/s
Show Answer
Correct Answer: D [50 m/s]
Notes:
The speed of the train, given in kilometers per hour, is to be converted to meters per second. We use the conversion formula which states that 1 km/hr is equal to 5/18 m/s. Using the formula, we get (180 x 5)/18, which equals 50 m/s. This conversion is often applied in physics to accurately measure speed or velocity in different units for a variety of calculations, such as computation or comparison of speeds of different objects moving at varying velocities.
2. How the brain interprets the frequency of an emitted sound is called its __:
[A] Pitch
[B] Amplitude
[C] Intensity
[D] Timbre
Show Answer
Correct Answer: A [ Pitch]
Notes:
How the brain interprets the frequency of an emitted sound is called the pitch. Researchers have discovered a discrete region of the monkey brain that processes pitch, the relative high and low points of sound, by recognizing a single musical note played by different instruments.
3. Two pieces of ice at 0°C would freeze together if pressed against each other and then released. In this context, which among the following is the correct principle in action in this?
[A] The melting point of pure ice decreases with pressure.
[B] The melting point of pure ice increases with Pressure
[C] The melting point of pure ice first increases, then decreases with pressure
[D] The melting point of pure ice first decreases then increases with pressure
Show Answer
Correct Answer: A [ The melting point of pure ice decreases with pressure.]
Notes:
Melting point of pure ice decreases with pressure at the rate of 0.0072°C per atmosphere and this is called regulation, which was discovered by Faraday and occurs at some 0°C or very slightly less temperature.
4. Echoes are heard when we shout in an empty hall. But when the hall is full of people no echoes are heard why?
[A] Echoes are subdued in the noise of people
[B] Soft clothes of people absorb sound instead of reflecting it
[C] Destructive interference of sound takes place
[D] Excessive reverberations take place
Show Answer
Correct Answer: D [ Excessive reverberations take place]
Notes:
When we shout in an empty hall, we hear your own sound after a short time. This is because the empty room reflects the sound, so there is an echo.
When a hall is full of people, the sound produced is reflected multiple times by the people. This causes the sound to overlap with the original sound, so the listener can’t distinguish between the two.
For an echo to be heard, the surfaces need to reflect the sound, or there needs to be more clarity. For example, big open spaces are good for hearing echoes.
5. Which of the following laws state that the orbits of the planets are ellipses, with the Sun at one focus of the ellipse?
[A] Kepler’s First law
[B] Kepler’s Second law
[C] Kepler’s Third law
[D] None of the above
Show Answer
Correct Answer: A [Kepler’s First law]
Notes:
Kepler’s First law: It is also known as law of orbits. It states that every planet revolves around the sun in an elliptical orbit. The sun is situated at one foci of the ellipse.
6. Which of the following is NOT an application of principle of floatation?
[A] Ships
[B] Balloons
[C] Submarines
[D] None of the above
Show Answer
Correct Answer: D [None of the above]
Notes:
The principle of floatation states that a floating object displaces its own weight of the fluid in which it floats. Some of the applications of the principle of Floatation:- 1. Ships 2. Balloons 3. Submarines
7. In which of the following positions is the potential energy minimum in S.H.M?
[A] Extreme position
[B] Mean position
[C] can be at extreme or mean position
[D] None of the above
Show Answer
Correct Answer: B [Mean position]
Notes:
Potential energy maximum and equal to total energy at extreme positions. Potential energy is minimum at mean position.
8. By what phase angle the velocity is ahead of displacement in S.H.M?
[A] π
[B] π/4
[C] π/2
[D] 2π
Show Answer
Correct Answer: C [π/2]
Notes:
In S.H.M. the velocity is ahead of displacement by a phase angle π/ 2, the acceleration is ahead of velocity by a phase angle π/ 2 and the acceleration is ahead of displacement by a phase angle of π.
9. What is the direction of electric and magnetic fields in an electromagnetic wave?
[A] parallel to each other
[B] perpendicular to each other
[C] at 45° to each other
[D] at 120° to each other
Show Answer
Correct Answer: B [perpendicular to each other]
Notes:
Electric and magnetic fields in an electromagnetic wave are perpendicular to each other and to the direction of propagation.
10. Which of the following is correct about compressions in sound wave?
[A] compressions are regions of low pressure and low density
[B] compressions are regions of high pressure and low density
[C] compressions are regions of high pressure and high density
[D] compressions are regions of low pressure and high density
Show Answer
Correct Answer: C [compressions are regions of high pressure and high density]
Notes:
Compressions are the regions where particles are crowded together and represented by the upper portion of the curve. Compressions are regions where density as well as pressure is high.
