Tag: physics

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Multiple choice types of cells electricity physics

To remove the polarisation defect in Daniel cell ?

  1. Zinc rod is coated with a thin layer of mercury

  2. Potassium bi-chromate is used

  3. The cell should be kept in open air

  4. Copper-sulphate is used
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A depolarizer in electrochemistry is a synonym of electroactive substance, i.e., a substance which changes its oxidation state, or partakes in a formation or breaking of chemical bonds, in a charge-transfer step of an electrochemical reaction. In the cells, the term "depolarizer" has been used to denote a substance used in a primary cell to prevent buildup of hydrogen gas bubbles.

The hydrogen ions displace metal from the salt so that metal, instead of hydrogen, is deposited on the positive plate. For example, copper-sulphate in Daniel cell.

Multiple choice types of cells electricity physics

In a cell, by convention, electron is taken to be flowing from

  1. positive electrode to negative electrode.

  2. negative electrode to positive electrode.

  3. both A and B

  4. none of the above.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

By convention, current is assumed to travel from positive to negative direction. The electrons travel from negative to positive. The direction of current is not the same as direction of flow of electrons; they are opposite.

Multiple choice types of cells electricity physics

Which among the following is a standard cell ?

  1. Daniel cell

  2. Cadmium cell

  3. Leclanche cell

  4. Lead accumulator
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The ideal qualities of standard cells as follows:
(1) The cells must be constructed from high purity materials and be reproducible.
(2) Except when current is flowing there should be no chemical reaction taking place in the cell.
(3) When the cell is thermally cycled it must give the same emf at a given temperature regardless of its thermal history.
(4) When a current is passed through the cell, its emf may change, but it must recover rapdidly and completely on cessation of the current.

(1) to (4) above represent an ideal qualities which only the Weston Standard cell approaches. The Weston Standard cell is constructed with the basic materials- mercury, cadmium, sulfuric acid, and water- are all purified by distillation, starting with the purest materials available. Hence out of given cells cadmium cell is the standard cell.

Multiple choice types of cells electricity physics

In daily life, dry cell is used in 

  1. Fan

  2. Alarm clock

  3. Tubelight

  4. All out(Mosquito repellant)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Alarm clock uses Dry Cell. Rest of the components work on power supply.

Multiple choice types of cells electricity physics

When the ends of metal wire are not connected to a battery

  1. electrons move from positive electrode to negative electrode.

  2. electrons move from negative electrode to positive electrode.

  3. electrons move in random directions.

  4. protons move in random direction in such a way that their net movement in a unit volume is zero.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When the ends of the metal wire are not connected to a battery, no electric field is produced inside the wire. Thus no force acts on the electrons in the wire. So the electrons collide with each other and move in random directions.

Multiple choice types of cells electricity physics

Nickel Cadmium cells are used in

  1. very long-life applications

  2. devices with high limitation on spaces.

  3. portable machines that run on electricity.

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

Nickel cadmium cells are used in portable machines that run on electricity. It is rechargeable.

Multiple choice types of cells electricity physics

Button cell is also called as

  1. lithium cell.

  2. nickel-cadmium cell

  3. dry cell

  4. leclanche cell
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lithium cell has a negative plate of lithium iron phosphate and a positive plate of carbon. It is also called as button cell.

Multiple choice types of cells electricity physics

When an electron moves from negative electrode to positive electrode

  1. negative charge moves from negative electrode to positive electrode.

  2. positive charge moves from positive electrode to negative electrode.

  3. no charge flows from either electrode to other electrode.

  4. both A and B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Electrons are termed as negative charged particles. Thus when electrons move from negative electrode to positive electrode, we say that negative particles move from negative electrode to positive electrode. On the other hand, the positive charges get attracted towards the negative electrode, thus they move from positive electrode to negative electrode.

Multiple choice types of cells electricity physics

Which one works with the help of dry cell?

  1. Torches

  2. Transistors, toys

  3. T.V.remotes

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Dry cells (Leclanche cells) are portable power sources commonly used in low-drain devices like torches, toys, and remote controls.

Multiple choice types of cells electricity physics

State whether true or false:
The used up chemicals in a dry cell can be re-obtained by charging it.

  1. True

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

Dry cell are not rechargeable.