Tag: electric current through conductors

Questions Related to electric current through conductors

What is the $-$ve terminal of dry cell made up of?

  1. Carbon rod

  2. Zinc plate

  3. Magnesium plate

  4. Cadmium rod


Correct Option: B
Explanation:
The dry cell consists of a zinc can, electrolyte paste, and a carbon rod in the center. A chemical reaction takes place between the zinc can and the paste. Electrons flow from the negative (zinc) terminal to the positive (carbon) terminal. Electrons are then pumped back to the negative terminal.

In secondary cells:

  1. Chemical changes can be reversed by heating electrodes

  2. Chemical changes can be reversed by passing electric current

  3. Current is produced by photo chemical reactions

  4. None of these


Correct Option: B
Explanation:

Answer is B.

When a primary cell is used, chemical reactions in the battery use up the chemicals that generate the power; when they are gone, the battery stops producing electricity and is useless. In contrast, in a secondary cell, the reaction can be reversed by running a current into the cell with a battery charger to recharge it, regenerating the chemical reactants. 

Three types of electric cells which provide current are:

  1. Button cell, solar cell & secondary cell

  2. Solar cell, electrolytic cell, electro chemical cell

  3. $(A)$ and $(B)$ both are correct

  4. Neither $(A)$ nor $(B)$ is correct


Correct Option: C
Explanation:

Answer is C.

When a primary cell is used, chemical reactions in the battery use up the chemicals that generate the power; when they are gone, the battery stops producing electricity and is useless. In contrast, in a secondary cell, the reaction can be reversed by running a current into the cell with a battery charger to recharge it, regenerating the chemical reactants. 
The types of cells mentioned in option A and option are correct.
Hence, option C is correct.

What is the direction of flow of current inside a dry cell?

  1. from $+$ve to $-$ve terminal

  2. from $-$ve to $+$ve terminal

  3. from $+$ve to $+$ve terminal

  4. from $-$ve to $-$ve terminal


Correct Option: B
Explanation:
The dry cell consists of a zinc can, electrolyte paste, and a carbon rod in the center. A chemical reaction takes place between the zinc can and the paste. Electrons flow from the negative (zinc) terminal to the positive (carbon) terminal. Electrons are then pumped back to the negative terminal.

The cartridge in a dry cell contains :

  1. manganese dioxide and ammonium chloride

  2. manganese dioxide and zinc dust

  3. ammonium chloride and zinc dust

  4. manganese dioxide and activated carbon


Correct Option: D
Explanation:

The cartridge in a dry cell contains manganese dioxide and activated carbon .

State whether true or false.
In a dry cell, the zinc container acts as the positive electrode.

  1. True

  2. False


Correct Option: B
Explanation:

In a dry cell, the zinc container acts as positive electrodes.T his statement is false.

The longer lead of a LED is always connected to the negative terminal of the battery and the shorter lead is connected to the posltlve terminal of the battery

  1. True

  2. False

  3. Ambiguous

  4. Data insufficient


Correct Option: B
Explanation:

Answer is B.
The LED bulb has two leads. The lead connected to the positive terminal of battery is called anode and the lead connected to the negative terminal is cathode. The slightly longer lead than the other is always connected to the positive terminal and the shorter lead is connected to the negative terminal.
Hence, the given statement is false.

For a resistance R and capacitance C in series the impedence is twice that of a parallel combination of the same elements.The frequency of the applied emf shall be.

  1. $\dfrac{{2\pi }}{{Rc}}$

  2. $\dfrac{1}{{2\pi {R _1}c}}$

  3. $\dfrac{{2\pi }}{{\sqrt {RC} }}$

  4. $\dfrac{1}{{2\pi \sqrt {RC} }}$


Correct Option: A

Two non ideal batteries are connected in series. Consider the following statements
(A) The equivalent emf is larger than either of the two emfs.
(B) The equivalent internal resistance is smaller than either of the two internal resistances.

  1. Both A and B are correct

  2. A is correct but B is wrong

  3. B is correct but A is wrong

  4. Both A and B wrong


Correct Option: B
Explanation:

If we add two non ideal batteries in series then
so in case (a) the equivalent e.m.f.  may be larger than either of two e.m.f., but in case (b) the equivalent e.m.f. may be smaller than either of two e.m.f.
In series total resistance is always greater than individual resistance, whether batteries are connected in any way 

[i.e. either according to case (a) or case (b)].

When cells are connected in series greater emf is obtained in the circuit.

  1. True

  2. False


Correct Option: A
Explanation:

When two or more cells are connected in series in a circuit, the total potential difference is the sum of their potential differences. Hence, the cells are connected in series in order to produce a larger total emf.