Tag: electricity

Quizzes (16) Questions (87)

Questions Related to electricity

Multiple choice types of cells electricity physics

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)

  1. $19.06$g
  2. $38.12$g
  3. $1.906$g
  4. $3.812$g
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice types of cells electricity physics

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

  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.
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice types of cells electricity physics

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

  1. Internal resistance 'r'

  2. Half of the internal resistance 'r'

  3. Two times of initial resistance 'r'

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to the Maximum Power Transfer Theorem, the power delivered to an external load is maximized when the load resistance equals the internal resistance of the source. This is derived by setting the derivative of power with respect to R to zero.

Multiple choice types of cells electricity physics

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 

  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. $\left( E-V \right) r$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The terminal voltage V is given by V = E - Ir, where I = V/r_ext. Substituting I, we get V = E - (V/r_ext) * r_int. Rearranging for r_int gives r_int = (E - V) * r_ext / V. The provided options use 'r' as the external resistance.

Multiple choice types of cells electricity physics

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

  1. $0.5 W$
  2. $1 W$
  3. $4 W$
  4. $2 W$
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice types of cells electricity physics

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

  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.
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

Multiple choice types of cells electricity physics

Primary cell are connected in parallel to

  1. Increase voltage

  2. Decrease capacity

  3. Decrease internal resistance

  4. Make electric current constant
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

Multiple choice types of cells electricity physics

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

  1. $1.5 V$
  2. $2.5 V$
  3. $1.1 V$
  4. $-1.1 V$
Reveal answer Fill a bubble to check yourself
A Correct answer
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.
Multiple choice types of cells electricity physics

The depolariser used in Laclanche cell is

  1. Solution of ammonium chloride

  2. Porous pot

  3. Powdered carbon

  4. Manganese dioxide
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

Multiple choice types of cells electricity physics

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

  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.
Reveal answer Fill a bubble to check yourself
B Correct answer
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.