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. What is the focal length of a concave lense with number -5D?
[A] 5 cm
[B] 10 cm
[C] 15 cm
[D] 20 cm
Show Answer
Correct Answer: D [20 cm]
Notes:
A concave lens is a type of lens that has a thinner center than edges, and it is sometimes called a diverging lens because it spreads out light rays that are parallel to its axis. The focal length of a lens is a measure of its ability to focus light, and it is defined as the distance from the lens to the point where the light rays converge. In the case of a concave lens with a power of -5D, the focal length would be equal to 1/5 of a meter, or 20 centimeters.
2. When a tubelight breaks, a cracking sound is produced because ____?
[A] Pressure inside the lamp is less than atmospheric pressure
[B] Pressure inside the lamp is more than atmospheric pressure
[C] The lamp is filled with reactive gases
[D] The lamp is filled with mercury vapour
Show Answer
Correct Answer: A [Pressure inside the lamp is less than atmospheric pressure ]
Notes:
A fluorescent lamp tube is filled with a gas containing low pressure mercury vapor and argon, xenon, neon, or krypton. The pressure inside the lamp is around 0.3% of atmospheric pressure.
3. Mach number is a measure of which of the following?
[A] Speed
[B] Heat Transfer
[C] Static Pressure
[D] Volume
Show Answer
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. In context with electromagnetism, which among the following is a correct definition of Permeability?
[A] Ability of a material to repel magnetic field within itself
[B] Ability of a material to support the formation of a magnetic field within another body
[C] Ability of a material to support the formation of a magnetic field within itself
[D] Ability of a material to create magnetic dipoles
Show Answer
Correct Answer: C [Ability of a material to support the formation of a magnetic field within itself]
Notes:
Ability of a material to support the formation of a magnetic field within itself is Permeability. It is the measure of the resistance of a material against the formation of a magnetic field.
5. Which among the following Radio frequencies are used around the world in air navigational system?
[A] Very Low Frequency (VLF)
[B] Very High Frequency (VHF)
[C] Tetrahertz Radiation (THF)
[D] Ultra High Frequency (UHF)
Show Answer
Correct Answer: B [ Very High Frequency (VHF)]
Notes:
VHF (Very High Frequency) omnidirectional radio range (VOR), is a short-range radio navigation system for aircraft, enabling aircraft to determine their position and stay on course by receiving radio signals transmitted by a network of fixed ground radio beacons, with a receiver unit. Uses radio frequencies in the very high frequency (VHF) band from 108 to 117.95 MHz. VOR is the standard air navigational system in the world, used by both commercial and general aviation.
6. A container is filled with water at 4°C. The water will overflow if the temperature of water is __:
[A] Increased
[B] Decreased
[C] Increased or decreased
[D] None of them
Show Answer
Correct Answer: C [ Increased or decreased]
Notes:
The reason is the anomalous expansion of water. The maximum density of water occurs at 4°C. So the water expands whether it is heated above 4°C or cooled below 4°C.
7. kg m2is the unit of which of the following physical quantities?
[A] Linear Momentum
[B] Angular Momentum
[C] Angular Impulse
[D] Moment of Inertia
Show Answer
Correct Answer: D [ Moment of Inertia ]
Notes:
kg m2is the unit of Moment of Inertia. The moment of inertia is a physical quantity which describes how easily a body can be rotated about a given axis. It is a rotational analogue of mass. Moment of Inertia = mass x (radius of gyration)2
8. Which of the following conditions is true for two vectors to be collinear?
[A] Equal magnitude
[B] Same Direction
[C] Acting along the parallel straight lines
[D] Both a and c
Show Answer
Correct Answer: C [Acting along the parallel straight lines]
Notes:
Two vectors are said to be collinear if they are acting along the parallel straight lines. The collinear vectors may or may not have equal magnitude.
9. The forces acting at a point are called as:
[A] Collinear forces
[B] Coplanar forces
[C] Concurrent forces
[D] Unit forces
Show Answer
Correct Answer: C [Concurrent forces]
Notes:
The forces which are acting at a point are called as concurrent forces. Note: When concurrent forces in equilibrium act on a body, the state of the body shall remain unchanged i.e. if the body is at rest, it will continue to be at rest. Similarly, a body will continue to move uniformly along the same straight line, if concurrent forces in equilibrium are applied on the body.
10. What is the SI unit of acceleration due to gravity?
[A] ms-2
[B] ms-3
[C] Kgms-2
[D] ms-1
Show Answer
Correct Answer: A [ms-2]
Notes:
The acceleration due to gravity is the acceleration set up in the body when it falls freely under the effect of gravity alone. The SI unit of acceleration due to gravity is ms-2
