Tag: physics

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Multiple choice safety precautions to be taken while handling electricity electric charge and electric current physics ohm's law current electricity

The plate of earthing is surrounded by a mixture of _______to make a good earth connection. Fill in the blank. 

  1. Salt

  2. Charcoal

  3. Both

  4. None of the above 
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The copper plate is surrounded by a mixture of charcoal and salt to make a good earth connection. To keep the ground damp, water is poured through the pipe from time to time.

Multiple choice safety precautions to be taken while handling electricity electric charge and electric current physics ohm's law current electricity

If a person touches the appliance, his body provides a path for current to flow to earth which is at ............ potential.

  1. Infinite

  2. low

  3. high

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

 If a person touches the appliance, his body provides a path for current to flow to earth which is at zero potential.Thus, person may get severe shock which may prove fatal. Hence, fuse is connected to live wire so that if it melts, the appliance is no longer connected to the high potential of the supply and possibility of electric shock is eliminated.

Multiple choice safety precautions to be taken while handling electricity electric charge and electric current physics ohm's law current electricity

Why mostly all electrical home appliances like refrigerator, toaster etc. are provided with a wire having green insulation?

  1. Earth wire is the insulated green coloured copper wire which is connected to a metal plate deep inside the earth near the house.

  2. It is used as a safety measure.

  3. both

  4. none
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Earth wire is the insulated green coloured copper wire which is connected to a metal plate deep inside the earth near the house. It is used as a safety measure. It is kept at zero potential by connecting it to the ground, thus, providing a low-resistance conducting path for the current. When by electric fault, if current flows through the metallic body of electric appliance and we touch it, then current finds the lower resistance path of earth wire than our body. So, current flows through earth wire only and we remain safe.

Multiple choice safety precautions to be taken while handling electricity electric charge and electric current physics ohm's law current electricity

Many electrical appliances are earthed or grounded. Reason behind this

  1. to make electricity balance

  2. due to "g"

  3. protection against shock

  4. all
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In case of an earthed appliance, if there is any leakage of current or the line wire comes in contact with its body, then the current flows to the ground.

Multiple choice safety precautions to be taken while handling electricity electric charge and electric current physics ohm's law current electricity

State whether true or false.
In electrical circuits the earth is considered to be at infinite potential.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In an electrical circuit, the earth is considered as having $0(zero)$ potential.


This is considered because of very negligible charge density on earth surface when compared with our electrical circuit.

Given statement is $False$.

Multiple choice safety precautions to be taken while handling electricity electric charge and electric current physics ohm's law current electricity

The earth wire is connected to the outer casing of the appliance because ___________.

  1. The earth wire can prevent the fuse from blowing

  2. The earth wire can carry leaked charges to the ground

  3. The outer casing is an insulator and therefore it can store charges

  4. The earth wire can conduct the heat away from the appliance
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The earth terminal is connected to the metal casing so that the current goes through the earth wire instead of causing an electric shock. A strong current surges through the earth wire because it has a very low resistance. This breaks the fuse and disconnects the appliance

Multiple choice safety precautions to be taken while handling electricity electric charge and electric current physics ohm's law current electricity

The earth wire is connected to the outer casing of the appliance because ...................  .

  1. The earth wire can prevent the fuse from blowing

  2. The earth wire can carry leaked charges to the ground

  3. The outer casing is an insulator and therefore it can store charges

  4. The earth wire can conduct the heat away from the appliance
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The earth wire is connected to the outer casing of the appliance because the earth wire can carry leaked charges to the ground.The outer surface is usually made conducting and an earth wire takes the excess charge from the body to the earth which is a charge sink,thus preventing us from getting a shock due to charge buildup.