Tag: electricity

Questions Related to electricity

A $100$ watt, $110$ volt lamp is connected in series with an electrolytic cell containing $CaSO _4$ solution, the weight of Cd deposited by the current for $10$ hrs is (Sl.wt. of Cd=112.4)

types of cells electricity physics

  1. $19.06$g

  2. $38.12$g

  3. $1.906$g

  4. $3.812$g

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Correct Option: B

In an electric containing battery, the positive charge inside the battery.

types of cells electricity physics

  1. always goes from the positive terminal to the negative terminal

  2. may go from the positive terminal to the negative terminal

  3. always goes from the negative terminal to the positive terminal

  4. May go either side depending on the absolute value of the electric field.

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Correct Option: D

The power supplied by a battery (or source) is maximum when the external resistance 'R' is equal to the 

types of cells electricity physics

  1. Internal resistance 'r'

  2. Half of the internal resistance 'r'

  3. Two times of initial resistance 'r'

  4. None of these

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Correct Option: A

A cell of emf E is connected across a resistance r . The potential difference terminals of the cell is found to be V . The internal resistance of the cell must be 

types of cells electricity physics

  1. $\dfrac { \left( E-V \right) V }{ r } $

  2. $\dfrac { 2\left( E-V \right) V }{ r } $

  3. $\dfrac { \left( E-V \right) r }{ V } $

  4. $\left( E-V \right) r$

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Correct Option: C

A cell drives a current of 1 A in to load of resistance $4W$. On doubling the load resistance. the current is found to be reduced by $40 \%$. The internal resistance of the cell is

types of cells electricity physics

  1. $0.5 W$

  2. $1 W$

  3. $4 W$

  4. $2 W$

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Correct Option: A

The Zinc rod in leclanche cell is coated with a thin layer of mercury because

types of cells electricity physics

  1. The defect of polarization is removed.

  2. The defect of local action is removed.

  3. The cell does not remain dirty.

  4. The cell is brightened.

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Correct Option: B
Explanation:

Local Action is the tendency for the chemically active components of a cell to react with each other, and so become exhausted even when no current is being drawn from the cell. Local action has the effect of reducing the 'shelf-life' of the cell - it uses up its chemical reserves and becomes exhausted even when not being used.

In a cell formed from zinc and copper electrodes suspended in a weak acid solution, local action can be seen. The zinc becomes coated with hydrogen bubbles, as a result of its reacting with the acid, even when no current is being drawn. After a while either the zinc will be entirely consumed, or the acid will be neutralised. To avoid this, a thin layer of mercury is coated on zinc rod.

Primary cell are connected in parallel to

types of cells electricity physics

  1. Increase voltage

  2. Decrease capacity

  3. Decrease internal resistance

  4. Make electric current constant

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Correct Option: C
Explanation:

Equivalent resistance of parallel combination         $\dfrac{1}{R _{eq}}  = \dfrac{1}{R _1}+\dfrac{1}{R _2} + .......$


$\implies$ Equivalent resistance of the parallel combination is less than the minimum of the individual resistance used.

Hence primary cell are connected in parallel to decrease the internal resistance.

What is the e.m.f. of a dry cell ?

types of cells electricity physics

  1.  $1.5 V$

  2. $2.5 V$

  3.  $1.1 V$

  4. $-1.1 V$

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Correct Option: A
Explanation:
A common dry cell is the zinc–carbon battery, sometimes called the dry Leclanché cell, with a nominal voltage of 1.5 volts, the same as the alkaline battery (since both use the same zinc–manganese dioxide combination).Hence the correct option A.

The depolariser used in Laclanche cell is

types of cells electricity physics

  1. Solution of ammonium chloride

  2. Porous pot

  3. Powdered carbon

  4. Manganese dioxide

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Correct Option: D
Explanation:

A battery depolarizer takes up electrons during discharge of the cell and thus it is always an oxidizing agent. The term depolarizer has been used to denote a substance used in primary cell to prevent build up of hydrogen gas bubbles. Manganese dioxide is used as depolarizer in Leclanche cell and dry cell.

When the two terminals of a battery are connected directly with a wire then:

types of cells electricity physics

  1. more electrical energy is stored in the cell

  2. the chemical energy stored get used up very fast.

  3. no current flows in the wirc

  4. none of these.

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Correct Option: B
Explanation:

Battery is the source of potential difference and wire is a conductor but can't be a perfect conductor. It has some resistance in which voltage gets dropped. As resistance of wire is much smaller so it will be large amount of current through battery and battery will get discharged much sooner.the chemical energy stored get used up very fast.