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Multiple choice physics applications of electromagnets

Electromagnets are used in

  1. electric bells only

  2. telephones only

  3. dynamos only

  4. all the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An electromagnet is a soft metal core made into a magnet by the passage of electric current through a coil surrounding it. It has a number of applications including electric bells, in telephones and in dynamos.

Multiple choice physics applications of electromagnets

Electromagnets are used in

  1. electric bells only.

  2. telephones only.

  3. dynamos only.

  4. all the above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Electromagnets are fundamental components in electric bells, telephones, and dynamos, as they allow for the conversion of electrical energy into mechanical motion or magnetic fields.

Multiple choice physics applications of electromagnets

In which of the following devices is an electromagnet used?
a. Electric tram
b. Loud speaker
c. Telegraph
d. Relay microphone

  1. a

  2. b, c and d

  3. a and b

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An electromagnet is a temporary strong magnet made from a piece of soft iron when current flows in the coil wound around it. It is an artificial magnet and loses its magnetism when the current is removed. It is used in electric trams, loud speakers, telegraph, relay microphone etc to enhance the effect.

Multiple choice physics applications of electromagnets

Match the following

1. Industrial use a. Study of magnetic properties under magnetic field
2. Scientific use b. Removing pieces of iron from wounds
3. Medical use c. To separate iron filaments from other waster
4. Easiest method d. Lifting and transporting heavy loads of iron mass
  1. $1-d, 2-a, 3-b, 4-c$
  2. $1-b, 2-d, 3-c, 4-a$
  3. $1-c, 2-b, 3-a, 4-d$
  4. $1-a, 2-c, 3-d, 4-b$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Electromagnets are used for various industrial, scientific, medical purposes mentioned above.

Multiple choice physics applications of electromagnets

When the current through the electromagnet of a relay reaches a particular value.

  1. It breaks the circuit

  2. It opens the circuit by pulling in an iron contact

  3. It closes the circuit by pulling in an iron contact

  4. Both A or C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A relay is an electromagnetic switch. Depending on the design, the movement of the iron contact can either open or close a secondary circuit when the electromagnet is energized.

Multiple choice physics heat and energy zeroth law of thermodynamics

Two bodies A and B are said to be in thermal equilibrium with each other, if :

  1. heat flows from A to B

  2. heat flows from B to A

  3. both the bodies lose equal amounts of heat to the atmosphere

  4. heat does not flow from either A or B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The correct answer is option(D).

Thermal equivalence happens when there is no temperature difference between two bodies. And no heat transfer happens.

Multiple choice physics heat and energy zeroth law of thermodynamics

For 2 gases in thermal equilibrium with each other , Pressure of the gases 

  1. varies as speed of the gas molecules

  2. varies as square root of the gas molecules

  3. varies inversely as the gas molecules

  4. remains same
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

For the ideal gas equation $PV=nRT$

if T is constant the pressure is also constant
hence  when the gases in thermal equilibrium have same temperature their pressure remains same .
 hence option D is correct.

Multiple choice physics heat and energy zeroth law of thermodynamics

Two systems are in thermal equilibrium. The quantity which is common for them is

  1. heat

  2. momentum

  3. specific heat

  4. temperature
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Thermal equilibrium implies that there is no heat transfer taking place between the given two bodies i.e. there temperature is same.

Multiple choice physics heat and energy zeroth law of thermodynamics

When a gas  is in thermal equilibrium, its molecules

  1. have the same average kinetic energy.

  2. have different energies which remains constant.

  3. have a certain constant energy.

  4. do not collide with one another.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When a gas is in thermal equilibrium, the temperature throughout the gas is the same. (Zeroth law of thermodynamics)
The average kinetic energy of the gas molecules is directly proportional to the absolute temperature of the gas. I.e. different sections of the gas will all have the same average kinetic energy.

Multiple choice physics heat and energy zeroth law of thermodynamics

Two metal spheres of different radii having same temperature are placed in thermal contact in a vaccum. Which of the following quantities is certainly correct?

  1. Each sphere has the same internal energy

  2. There is no net transfer of thermal energy between the spheres

  3. Both spheres radiate electromagnetic energy at the same rate

  4. The larger sphere a greater mean internal energy per atom than the smaller sphere
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

There is no net transfer of thermal energy between the spheres.

Option B is correct.