Physics Quiz 4
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- Question 1 of 50
A kilowatt-hour is a unit of:
The kilowatt-hour (kWh) is a unit of energy equal to one kilowatt of power sustained for one hour and is commonly used as a measure of electrical energy. One kilowatt-hour is equal to 3600 kilojoules.
- Question 2 of 50
Ventilators are provided near the ceiling of the room because:
Ventilation is mainly used to control indoor air quality, temperature, humidity, and air motion. It is provided near the ceiling of the room because the exhaled warmer air rises up and goes out.
- Question 3 of 50
The hair of a shaving brush clings together when removed from water due to:
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. The hair of a shaving brush clings together when removed from water due to Surface tension.
- Question 4 of 50
In the process of magnetisation of a bar:
In the process of magnetization of a bar, the entire bulk of the bar gets magnetised. By the process of magnetisation, the formed pieces develop North polarity on one end or side and South polarity on the other end or side, in a very short period of time.
- Question 5 of 50
A falling drop of rainwater acquires the spherical shape due to:
Raindrops start to form in a roughly spherical structure due to the surface tension of water. Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible.
- Question 6 of 50
The weakest of all fundamental forces is:
Gravitational Force is the weakest of the four fundamental forces. Ordered from strongest to weakest, the forces are: 1) the strong nuclear force, 2) the electromagnetic force, 3) the weak nuclear force, and 4) Gravitational Force.
- Question 7 of 50
The velocity of sound in air does not change with the change of:
The velocity of sound in the air does not change with the change of Pressure of gas (air). The speed of sound increases with the increase of the temperature of the medium.
- Question 8 of 50
Nanotechnology deals with objects with dimensions in the range of:
A nano particle is an ultra fine unit with dimensions measured in nano metres (1 nm = 10−9 metre).
- Question 9 of 50
Why is it difficult to breathe at higher altitudes?
Due to low air pressure, it is difficult to breathe at higher altitudes. The air at higher altitudes is colder, less dense, and contains fewer oxygen molecules.
- Question 10 of 50
The strongest force in nature is:
The strongest force in nature is nuclear force, also called the strong nuclear interaction. It is the strongest of the four fundamental forces of nature.
- Question 11 of 50
According to the theory of relativity, which of the following always remains constant?
The Special Theory of Relativity is based on Einstein’s recognition that the speed of light does not change even when the source of the light moves.
- Question 12 of 50
The spoon dropped by an astronaut in a satellite will:
The spoon dropped by an astronaut in a satellite will continue to follow the motion of the satellite. The reason that an object (spoon) will maintain its orbit, regardless of its position in the orbit, is because the gravitational force from the larger object (earth) will constantly act upon the smaller object, thereby pulling the smaller object towards the larger object.
- Question 13 of 50
A colour-blind person cannot:
A colour-blind person cannot distinguish between certain colours. Color blindness often happens when someone cannot distinguish between certain colors. This usually happens between greens and reds, and occasionally blues.
- Question 14 of 50
Pipelines in cold countries often burst in winter, because:
Water pipes in hilly areas often burst on a cold frosty night, because water in the pipes freezes and on freezing water expands in its volume, causing a significant amount of pressure buildup, so pipes break.
- Question 15 of 50
When a body is taken from earth to moon:
When a body is taken from earth to moon, weight changes but mass remains same. An object’s weight is dependent on its mass and how strongly gravity pulls on it. The strength of gravity depends on how far away one object is from another. That’s why the same object weighs different amounts on different planets.
- Question 16 of 50
A mirage occurs because of:
A mirage occurs because of total internal reflection by layers of air. When the ground is very hot and the air is cool. The hot ground warms a layer of air just above the ground. When the light moves through the cold air and into the layer of hot air it is refracted (bent). A layer of very warm air near the ground refracts the light from the sky nearly into a U-shaped bend.
- Question 17 of 50
Atomic power plant works on the principle of:
Nuclear reactors operate on the principle of nuclear fission, the process in which a heavy atomic nucleus splits into two smaller fragments. The nuclear fragments are in very excited states and emit neutrons, other subatomic particles, and photons.
- Question 18 of 50
Bolometer is used to measure:
A bolometer is an instrument for measuring radiation by means of the rise in temperature of a blackened metal strip in one of the arms of a resistance bridge.
- Question 19 of 50
A person is hurt on kicking a stone due to:
Newton’s third law states that when two bodies interact, they apply forces to one another that are equal in magnitude and opposite in direction. The third law is also known as the law of action and reaction. When we kick the stone, the stone exerts an equal and opposite force on the leg which hurts us.
- Question 20 of 50
The fuse in our domestic electric circuit melts when there is a high rise in:
The fuse breaks the circuit if a fault in an appliance causes too much current to flow. This protects the wiring and the appliance if something goes wrong. The fuse contains a piece of wire that melts easily.
- Question 21 of 50
Which of the following is an example of a cantilever beam?
A cantilever is any rigid object that is fixed at one end and extends out over empty space. Street signs, airplane wings, shelves, fan blades, and some bridges are all examples of cantilevers.
- Question 22 of 50
It is difficult to cook rice:
As altitude increases and atmospheric pressure decreases, the boiling point of water decreases. To compensate for the lower boiling point of water, the cooking time must be increased. Turning up the heat will not help cook food faster.
- Question 23 of 50
A dynamo is a device which:
A dynamo is an electrical generator that converts mechanical energy into electrical energy. It makes direct current electric power using electromagnetism.
- Question 24 of 50
A soap bubble shows colours when illuminated with white light. This is due to:
Interference may be defined as waves emerging from two different sources, producing different wavefronts. It is demonstrated by the light reflected from a film of oil floating on water. Another example is the thin film of a soap bubble, which reflects a spectrum of beautiful colors when illuminated by natural or artificial light sources.
- Question 25 of 50
The instrument used to see the distant objects on the Earth is:
The instrument used to see the distant objects on the Earth is a terrestrial telescope. Astronomical telescopes are used for viewing distant stars and planets whereas terrestrial telescopes are used for viewing distant objects on earth.
- Question 26 of 50
Which of the following substance is highly plastic?
Clay is a highly plastic substance. Clay particles are attracted to each other by weak electrostatic forces. Water conducts these forces. Thus, dry clay mixed with a fifth of its weight in water, becomes the plastic material clay artists use.
- Question 27 of 50
Which of the following principle is used to produce ‘low-temperatures’?
Adiabatic demagnetization is a process by which the removal of a magnetic field from certain materials serves to lower their temperature. It comes under magnetic cooling, exploiting paramagnetic properties to cool some materials down.
- Question 28 of 50
A photoelectric cell converts:
A photoelectric cell is a device that are used to convert light energy of the sun into electrical energy. It is an electron tube with a photosensitive cathode that emits electrons when illuminated and an anode for collecting the emitted electrons.
- Question 29 of 50
Two stones of different masses are dropped simultaneously from the top of a building:
All objects, regardless of mass, will fall at the same rate. Heavier things have a greater gravitational force AND heavier things have a lower acceleration. It turns out that these two effects exactly cancel to make falling objects have the same acceleration regardless of mass.
- Question 30 of 50
A concave lens always forms an image which is:
A concave lens is used to minimize the proportions of the objects and gives a wider view of the object or area. It always forms virtual, erect and diminished image.
- Question 31 of 50
The modulus of rigidity is the ratio of:
The modulus of rigidity, also known as shear modulus, is the ratio of shearing stress to shearing strain. It is the elastic coefficient when a shear force is applied resulting in lateral deformation.
- Question 32 of 50
The propagation of sound waves in a gas involves:
The propagation of sound waves in a gas involves adiabatic compression and rarefaction. Sound waves travel very quickly through mediums in cycles of compression and rarefaction. Therefore the expansion and compression takes place very quickly, causing a localized variation in temperature. This is the reason why the propagation of sound waves is an adiabatic process.
- Question 33 of 50
If input frequency of a full-wave rectifier be n, then output frequency would be:
A full-wave rectifier rectifies both the half cycles of the AC input i.e., it conducts twice during a cycle. Hence, output frequency would be double to that of input frequency. Thus, the output frequency of a full-wave rectifier would be 2n.
- Question 34 of 50
Heat transfer horizontally within the atmosphere is called:
Heat transfer horizontally within the atmosphere is called advection. Advection is the transfer of heat or matter by the flow of a fluid, especially horizontally in the atmosphere or the sea. The horizontal movement of the air is comparatively more significant than the vertical movement.
- Question 35 of 50
Noise is measured in:
Decibel (dB) is the unit used to express the intensity of sound. It is a unit for expressing the ratio between two physical quantities, usually amounts of acoustic or electric power, or for measuring the relative loudness of sounds.
- Question 36 of 50
The bats can fly in the dark because:
Bats can fly in the dark because they generate ultrasonic sound waves. Bats are guided by ultrasonic waves which they produce and enable them to fly in the dark.
- Question 37 of 50
What changes will happen to a bowl of ice and water kept at exactly zero degree Celsius?
The freezing and melting point of water is 0°C. The liquid form of water starts to become solid (ice) and solid (ice) starts to become liquid (water) at this temperature. Hence, at 0°C water exists in both liquid (water) and solid (ice) states.
- Question 38 of 50
The acceleration due to gravity at the equator:
Acceleration due to gravity is the acceleration gained by an object due to gravitational force. The value of acceleration due to gravity is least on the equator because the distance between the surface of the earth and its center is more at the equator than that at the poles.
- Question 39 of 50
The angle of friction and angle of repose are:
The angle of friction and angle of repose are equal to each other. The angle which the resultant of force of limiting friction F and normal reaction R makes with direction of normal reaction R is called angle of friction. Angle of repose is the steepest angle at which a sloping surface formed of loose material is stable.
- Question 40 of 50
If a boy sitting in a train, which is moving at a constant velocity, throws a ball straight up into the air, the ball will:
Due to inertia of motion, as long as the ball stays in the air, both the boy and the ball move in the same direction which cause the ball falls into his hand.
- Question 41 of 50
Intensity of gravitational field of earth is maximum at:
The intensity of the Gravitational field of the Earth is maximum at the poles and it is minimum at the equator because the distance between the surface of the earth and its center is maximum at the equator and it is minimum at the poles.
- Question 42 of 50
The spokes used in the wheel of a bicycle increase its:
The spokes used in the wheel of a bicycle increase its moment of inertia due to the increase in the distribution of mass. This opposes the change in the rotary motion of the wheel. Thus spokes fitted to the cycle wheel give a steady motion.
- Question 43 of 50
A transformer works on the principle of:
A transformer works on the principle of mutual induction. The core of the transformer works to direct the path of the magnetic field between the primary and secondary coils to prevent wasted energy. Once the magnetic field reaches the secondary coil, it forces the electrons within it to move, creating an electric current via electromotive force (EMF).
- Question 44 of 50
The sky appears blue because:
The sky appears blue to the human eye as the short waves of blue light are scattered more than the other colours in the spectrum, making the blue light more visible.
- Question 45 of 50
The device in communication satellites which receives signals from an earth station and transmits them to different directions is:
A communications satellite’s transponder is the series of interconnected units that form a communications channel between the receiving and the transmitting antennas. It is mainly used in communication satellite to receives signals from an earth station and transmits them to different directions.
- Question 46 of 50
When a ship enters the sea from a river:
When a ship enters the sea from a river it rises a little because seawater has more density than river water. Due to the higher density of seawater, the upthrust produced by the seawater on the ship is greater as compared to that produced by river water.
- Question 47 of 50
Two stones of unequal masses are thrown vertically up with the same velocity. Which of the following will happen?
When a body is thrown upward, the height attained by that body is independent of the mass and depends on the initial speed of the body and the value of g. So, two stones of unequal masses are thrown vertically up with the same velocity they will reach the same height.
- Question 48 of 50
The centre of gravity of a sprinter during the race lies:
The centre of gravity of a sprinter during the race lies ahead of his feet. It is an imaginary point in a body of matter where the total weight of the body may be thought to be concentrated. Running with a lean allows gravity to pull the runner forward.
- Question 49 of 50
Cloudy nights are warmer compared to clear nights, because clouds mainly:
Cloudy nights are warmer compared to clear nights because of radiation. On Cloudy nights, clouds warm the Earth by absorbing infrared radiation emitted from the surface and reradiating it back down.
- Question 50 of 50
A metal plate with a circular hole at the centre is heated. What will happen to the area of the hole?
A metal plate with a circular hole at the centre is heated, then the hole will expand in the same ratio as the metal. This is because the metal plate does not expand radially from the hole, it expands along the circumference i.e. the circumference of the ring expands in the same ratio as the width of the plate.