# Circuit, Current electricity questions and answers

1. What is a circuit in electric current?

Answer: A circuit is part through which electric currents flow.

2. List the type of circuit and explain them

Answer: Open , closed and short circuits

Open circuits: A circuit is said to be open when there is gap between the sources and loads, so that there will be no flow of current.

Short circuits: A circuit is said to be short circuited when, the terminals of source are connected together without any load (bulb) connected to the circuit.

Closed circuit: A circuit is said to be closed when there is no gap between the source and circuit component like bulb, so that the current will flow from the source and light up the lamp or bulb.

3. What is E.M.F?

Answer: E.M.F stands for electro motive force, and is defined as the magnitude of potential difference of both the external circuits and the inside of cells.

4. Differentiate between galvanometer and Ammeter

Answer: The galvanometer is used in measuring small electric current, while Ammeter is used in measuring larger electric current

5. Define the following: Insulator, resistor and, conductor

Answer: Insulator is any material that does not allow the passage of electric current through it. Examples are plastic, ceramics rubber e.tc

Conductor is any material that allows the passage of electric current through it. Examples, are copper, still, gold etc.

Resistor, can be described as a load (bulb) in electric circuit

6. What is the resistivity of a material?

Answer: It is the ability of any material to oppose the flow of current. It is given mathematically as

ρ =RA/L, where ρ =resistivity, R= resistance, A =crossectional area and L = the length of the wire

7. What is internal resistance?

Answer: Internal resistance can be defined as a resistance of a cell when it is not supplying any current. It can also be called lost volts.

8. Define Ohm’s law

Answer: Ohm’s law states that a current passing through a metallic conductor is directly proportional to the potential difference across the two terminals provided the temperature is kept constant.

That is V=IR, where V=potential difference measured in volts, I=current measured in ampere, and R =resistance measured in ohms.

9. What is junction or node in electric circuit?

Answer: Junction or node is a point in circuits where three or more connecting wire meet

10. State Kirchhoff’s f current law

Answer: It states that the sum of currents entering a circuit’s junction or node is equal to the sum of the currents leaving the circuit’s junction or node.  Or it  can be stated that the algebraic sum of the currents flowing into any junction is equal to zero. That is SI =o, where I =current

11. Define Kirchhoff’s voltage law

Answer: Kirchhoff’s voltage law states that the algebraic sum of the e.m.f in a closed loop of electrical network is equal to the algebraic sum of the voltages (IR) drops in the loop. That is

SE = SIR, Where I=current and R =resistance

12. What is Wheatstone’s bridge

Answer: It is a circuit bridge designed by Wheatstone, which measure accurately the resistance of a resistor. This bridge consists of four resistors.

13. What is potentiometer?

Answer: It is a device used in measuring and comparing e.m.f of cells

14. The instrument used in measuring potential difference is known as what?

15. The electrical energy supplied by a Leclanche cell is obtained from.

A. Mechanical energy

B. Chemical energy

C. Solar energy

D. Magnetic energy

16. In photo cell light energy is converted to

A. Kinetic energy

B. Heat energy

C. Chemical energy

D. Electrical energy

17. What is a cell?

Answer: A cell is a device for converting chemical energy in electrical energy

18. What are the two ways cells and resistance can be connected in a circuit?

Answer: They can be connected in circuit, in series or parallel.

19. The unit of resistance is what?

20. A group of cells is called what?

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