Physics Questions

Q:

Electrical burns occur principally because of

A) Radiation pulses of the electricity B) The heat generated by the flow of electrical current through the body
C) The high energy of electrons D) All of the above
 
Answer & Explanation Answer: B) The heat generated by the flow of electrical current through the body

Explanation:

Electrical burns occur principally because of the heat generated by the flow of electrical current through the body.

 

Burns caused by electricity are divided into three types:

electrical burns,

arc burns, and

thermal contact burns.

 

Electrical burns can result when a person touches electrical wiring or equipment that is used or maintained improperly.

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Q:

A cup of hot coffee is placed on a metal table in a room. By which of the following methods does it lose heat?

A) conduction and convection only B) conduction and radiation only
C) convection and radiation only D) conduction, convection and radiation
 
Answer & Explanation Answer: D) conduction, convection and radiation

Explanation:

Part of the heat is conducted away by the metal table. Convection currents in air near the surface of the coffee are set up which accounts for some heat loss. Heat is also lost by radiation from the hot coffee to the surroundings. Most of the heat is lost by the last method.

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Q:

A bimetal made copper and iron strips welded together is straight at room temperature. It is held vertically with iron strip towards left and copper strip towards right. If this bimetal is heated , it will

A) remain straight B) bend towards right
C) bend towards left D) none of these
 
Answer & Explanation Answer: C) bend towards left

Explanation:
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Q:

Electrical Pressure is also called

A) Current B) Voltage
C) Resistance D) Power
 
Answer & Explanation Answer: B) Voltage

Explanation:

Electrical Pressure is also called as Voltage. Voltage is measured in Volts.

 

Volt : A unit of electrical pressure or Voltage is called Volt.

 

One volt is the amount of pressure required to cause one ampere of current to flow against one ohm of resistance.

 

Voltage is also referred to as Electromotive Force or Electrical Potential or Electrical Pressure.

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Q:

Slip rings are usually made of

A) Aluminium B) Copper
C) Phosphor Bronze D) Carbon
 
Answer & Explanation Answer: C) Phosphor Bronze

Explanation:

A Slip ring is a ring in a dynamo or electric motor which is attached to and rotates with the shaft, passing an electric current to a circuit via a fixed brush pressing against it.

 

Slip rings are usually made of Phosphor Bronze.

 

Slip ring motors usually have a 'phase-wound' rotor. This type of rotor has a 3-phase, double-layer, distributed winding consisting of coils used in alternators. The rotor core is made up of steel laminations which have slots to accommodate formed 3-single phase windings.

slip_rings_are_usually_made_of1535005379.png image

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Q:

One light year is approximately equal to

A) 10^12 mts B) 10^16 mts
C) 10^11 mts D) 10^13 mts
 
Answer & Explanation Answer: B) 10^16 mts

Explanation:

Light year is the unit of to express astronomical distances, that light can travel in one year. Light moves at a velocity of about 300,000 kilometers (km) each second. So in one year, it can travel about 10 trillion km. More precisely, one light-year is equal to 9,500,000,000,000 kilometers.

 

Approximately, 1 light year = 10^16 mts.

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Q:

What device converts light energy to electrical energy?

A) Photodiode B) Photovoltaic cell
C) Thermocouple D) Heliostats
 
Answer & Explanation Answer: B) Photovoltaic cell

Explanation:

what_device_converts_light_energy_to_electrical_energy1555397376.png image

 

A device which is used to convert light energy directly into electrical energy is called as photovoltaic cell or a solar cell.

 

Heliostats convert light energy into heat energy.

 

A thermocouple is a device for measuring temperature.

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Q:

Heat is associated with

A) K.E of random motion of molecules B) K.E of orderly motion of molecules
C) Total K.E of random and orderly motion of molecules D) None of these
 
Answer & Explanation Answer: A) K.E of random motion of molecules

Explanation:
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