Tag: current electricity

Questions Related to current electricity

Earthing is also knows as

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

  1. Fusing

  2. Grounding

  3. Pluggings

  4. All

Show answer
Correct Option: B
Explanation:

Earthing, in other term, is also known as grounding.

State whether true or false:
Earthing of electric appliance prevents electric shock.

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

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Earthing ensure flow of charges directly to the ground through the earth wire thus protects us from getting any shock if it passes through us.

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

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

  1. Infinite

  2. low

  3. high

  4. zero

Show answer
Correct Option: D
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.

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

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

  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

Show answer
Correct Option: C
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.

Many electrical appliances are earthed or grounded. Reason behind this

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

  1. to make electricity balance

  2. due to "g"

  3. protection against shock

  4. all

Show answer
Correct Option: C
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.

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

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

  1. True

  2. False

Show answer
Correct Option: B
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 $False$.

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

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

  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

Show answer
Correct Option: B
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

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

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

  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

Show answer
Correct Option: B
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.

Ohm's law in vector form is :

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

  1. $V=I.R$

  2. $\overrightarrow { J } =\sigma \overrightarrow { E } $

  3. $\overrightarrow { J } =\rho \overrightarrow { E } $

  4. $\overrightarrow { E } =\sigma \overrightarrow { J } $

Show answer
Correct Option: B

In a meter bridge experiment, the ratio of the left gap resistance to right gap resistance is $2 : 3$, the balance point from left is?

physics current electricity meter bridge meter bridge and problems on it galvanometer

  1. $60$cm

  2. $50$cm

  3. $40$cm

  4. $20$cm

Show answer
Correct Option: C
Explanation:

Let $X$ is the left gap resistance and $R$ is the right gap resistance

$l _1$ be the balance point from left

From meter Bridge principle:-
$\implies \dfrac XR= \dfrac{l _1}{100-l _1}=\dfrac23$

$\implies 200-2l _1= 3l _1 \implies 200=5l _1$

$l _1= 40\ cm $

Hence option $(C)$ is correct