Tag: physics

Questions Related to physics

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.

Electro chemical equivalent of substance is 0.0006735 ; its eq. wt. is :

types of cells electricity physics

  1. 65

  2. 67.35

  3. 130

  4. cannot be calculated

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Correct Option: A

In a cell, electrons move from

types of cells electricity physics

  1. positive electrode to negative electrode.

  2. negative electrode to positive electrode.

  3. both A and B

  4. electrons do not move and only negative charge moves from one place to another place.

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Correct Option: B
Explanation:

We know that the current flows from positive electrode to negative electrode in a cell. The direction of electrons is always opposite to the direction of the current. Thus, the electrons move from negative electrode to positive electrode.  

Which one of the following statement is not true for Daniel cell ?

types of cells electricity physics

  1. The e.m.f. of this cell changes rapidly

  2. Some crystals of copper sulphate are added in it to make the solution saturated

  3. This cell was made first of all in 1850 by the scientist Daniel

  4. The hollow cylinder or the vessel of copper acts as the positive plate

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Correct Option: A
Explanation:

The e.m.f of a Daniel cell always remains constant and is equal to $1.08$ volts.

And  all the other statements given are true.

Direction of electric current inside the cell is from

types of cells electricity physics

  1. positive electrode to negative electrode.

  2. negative electrode to positive electrode.

  3. positive electrode to positive electrode.

  4. negative electrode to negative electrode.

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Correct Option: B
Explanation:

When an external circuit is connected across the cell, electrons flow from negative electrode to positive electrode(current flows opposite to this) in the external circuit. Inside the cell, negatively charged ions are attracted to negative electrode because it is depleted of electrons. Similarly, inside the cell, positively charged ions are attracted to positive electrode. 

Hence inside the cell, current flows from negative electrode to positive electrode.

The common dry cell produces a voltage of

types of cells electricity physics

  1. $1.5 V$

  2. $4 V$

  3. $2 V$

  4. $3 V$

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Correct Option: A
Explanation:

A common dry cell is zinc-carbon cell with a normal voltage of 1.5 V , same as the alkaline cell.

A battery converts chemical energy into

types of cells electricity physics

  1. mechanical energy

  2. solar energy

  3. electrical energy

  4. none of these

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Correct Option: C
Explanation:

A battery converts chemical energy into electrical energy.


Answer-(C)