Using water for putting out electric fires is risky, as the firemen can be electrocuted by the water jet. Water is a good conductor of electricity, and, the electric current flows through the water-jet directly into the hands of the person who is holding the waterhose, resulting in immediate electrocution.

Correct Option: A

Using water for putting out electric fires is risky, as the firemen can be electrocuted by the water jet. Water is a good conductor of electricity, and, the electric current flows through the water-jet directly into the hands of the person who is holding the waterhose, resulting in immediate electrocution.

Voltage gain, input impedance, output impedance, bandwidth etc. are few important characteristics of an amplifier. These parameters are more or less constant for a given amplifier. Quite often, the values of these parameters are required to be controlled. This can be conveniently achieved by employing a technique, called the feedback. Some of the advantages of negative feedback include: gain stability; reduced non-linear distortion, reduced noise, increased bandwidth, increased input impedance and reduced output impedance.

Correct Option: A

Voltage gain, input impedance, output impedance, bandwidth etc. are few important characteristics of an amplifier. These parameters are more or less constant for a given amplifier. Quite often, the values of these parameters are required to be controlled. This can be conveniently achieved by employing a technique, called the feedback. Some of the advantages of negative feedback include: gain stability; reduced non-linear distortion, reduced noise, increased bandwidth, increased input impedance and reduced output impedance.

The ionosphere is a part of the upper atmosphere and is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth.

Correct Option: C

The ionosphere is a part of the upper atmosphere and is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth.

Latent heat is the heat released or absorbed by a body or a thermodynamic system during a process that occurs without a change in temperature. A typical example is a change of state of matter, meaning a phase transition such as the melting of ice or the boiling of water. So water vapor which is the end product of evaporated water has latent heat.

Correct Option: B

Latent heat is the heat released or absorbed by a body or a thermodynamic system during a process that occurs without a change in temperature. A typical example is a change of state of matter, meaning a phase transition such as the melting of ice or the boiling of water. So water vapor which is the end product of evaporated water has latent heat.

The rifle and bullet have zero momentum and zero kinetic energy to start with. When the trigger is pulled, the bullet gains some momentum in the forward direction, but this is canceled by the rifle’s backward momentum, so the total momentum is still zero. The kinetic energies of the gun and bullet are both positive scalars, however, and do not cancel. The total kinetic energy is allowed to increase, because kinetic energy is being traded for other forms of energy. Some of the initial chemical energy of the gun powder, for example, is transformed into thermal energy and sound energy. From the relationship between kinetic energy and momentum, we know that if a massive particle and a light particle have the same momentum, the light one will have a lot more kinetic energy. If a light particle and a heavy one have the same velocity, the heavy one has more kinetic energy. Since the momentum of the gun and the bullet is same, the bullet which has a lower mass has a higher kinetic energy.

Correct Option: A

The rifle and bullet have zero momentum and zero kinetic energy to start with. When the trigger is pulled, the bullet gains some momentum in the forward direction, but this is canceled by the rifle’s backward momentum, so the total momentum is still zero. The kinetic energies of the gun and bullet are both positive scalars, however, and do not cancel. The total kinetic energy is allowed to increase, because kinetic energy is being traded for other forms of energy. Some of the initial chemical energy of the gun powder, for example, is transformed into thermal energy and sound energy. From the relationship between kinetic energy and momentum, we know that if a massive particle and a light particle have the same momentum, the light one will have a lot more kinetic energy. If a light particle and a heavy one have the same velocity, the heavy one has more kinetic energy. Since the momentum of the gun and the bullet is same, the bullet which has a lower mass has a higher kinetic energy.