A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power.The transistor invented in 1948 was well suited to the hearing aid application due to low power and small size; hearing aids were an early adopter of transistors. Transistors replaced the need for batteries in hearing aids.

Correct Option: C

A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power.The transistor invented in 1948 was well suited to the hearing aid application due to low power and small size; hearing aids were an early adopter of transistors. Transistors replaced the need for batteries in hearing aids.

The reason astronauts experience weightlessness which orbiting the earth in spaceships is that they are in free fall. A spacecraft in orbit is falling towards the Earth, because of gravity, but it is moving forward in its orbit fast enough that the path it follows is a curve that is a closed ellipse. Hence, the astronaut is not able to exert his mass on its surface. This condition is called weightlessness condition.If the spacecraft does not move quickly enough, it would fall prey to the effects of earth’s gravitational field and fall to the earth. Contrary to common misconception, there is no such thing as ‘Zero Gravity.’ Gravity is everywhere in the universe and manifests itself in black holes, celestial orbits, ocean tides, and even our own weight. The International Space Station, the space shuttle, and satellites are designed to stay in orbit, neither falling to the ground nor shooting off into space. Best option : (4) Orbital Motion

Correct Option: E

The reason astronauts experience weightlessness which orbiting the earth in spaceships is that they are in free fall. A spacecraft in orbit is falling towards the Earth, because of gravity, but it is moving forward in its orbit fast enough that the path it follows is a curve that is a closed ellipse. Hence, the astronaut is not able to exert his mass on its surface. This condition is called weightlessness condition.If the spacecraft does not move quickly enough, it would fall prey to the effects of earth’s gravitational field and fall to the earth. Contrary to common misconception, there is no such thing as ‘Zero Gravity.’ Gravity is everywhere in the universe and manifests itself in black holes, celestial orbits, ocean tides, and even our own weight. The International Space Station, the space shuttle, and satellites are designed to stay in orbit, neither falling to the ground nor shooting off into space. Best option : (4) Orbital Motion

A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction. When the brakes are applied, work is done by the friction force between the brakes and the wheels.

Correct Option: C

A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction. When the brakes are applied, work is done by the friction force between the brakes and the wheels.

Whenever, a current carrying conductor comes under a magnetic field, there will be force acting on the conductor and on the other hand, if a conductor is forcefully brought under a magnetic field, there will be an induced current in that conductor. In both of the phenomenon, there is a relation between magnetic field, current and force. This relation is directionally determined by Fleming Left Hand rule and Fleming Right Hand rule respectively.

Correct Option: D

Whenever, a current carrying conductor comes under a magnetic field, there will be force acting on the conductor and on the other hand, if a conductor is forcefully brought under a magnetic field, there will be an induced current in that conductor. In both of the phenomenon, there is a relation between magnetic field, current and force. This relation is directionally determined by Fleming Left Hand rule and Fleming Right Hand rule respectively.

The photoelectric effect is the propensity of highenergy electromagnetic radiation to eject electrons from a given material. The photoelectric effect has been utilized in devices called photocells, consisting of two electrodes in a sealed vacuum tube. By coating one electrode (the photocathode) with a alkali metal of low work function, a photo current could be generated even from visible light. Work function is the minimum energy needed to remove an electron from the surface of a material.

Correct Option: C

The photoelectric effect is the propensity of highenergy electromagnetic radiation to eject electrons from a given material. The photoelectric effect has been utilized in devices called photocells, consisting of two electrodes in a sealed vacuum tube. By coating one electrode (the photocathode) with a alkali metal of low work function, a photo current could be generated even from visible light. Work function is the minimum energy needed to remove an electron from the surface of a material.