Physics
Two identical bulbs are connected to different circuits. One bulb glows brighter than the other as it is connected to a cell of higher voltage.
(a) Why does the bulb connected to the higher voltage source glow brighter?
(b) What does potential difference represent?
(c) How does resistance affect electric current?
(d) Between a thin wire and a thick wire, which has greater resistance? Give reason.
Answer
(a) The bulb connected to the higher voltage source glows brighter because a higher potential difference drives more current through the bulb. As a result, more electrical energy is converted into light and heat per second, so the bulb glows more brightly.
(b) Potential difference represents the work done per unit charge in moving a charge between two points. It indicates how much energy is supplied to the charges to make them flow in a circuit.
(c) Resistance opposes the flow of electric current. According to Ohm’s law, for a given voltage, higher resistance results in lower current, while lower resistance allows more current to flow.
(d) A thin wire has greater resistance because it has a smaller cross-sectional area, which offers more opposition to the flow of electric current than a thick wire.
Related Questions
Assertion (A) : Current flows from body at higher potential to a body at lower potential.
Reason (R) : The direction of flow of electrons is from low potential body to a body at a higher potential.
- both A and R are true and R is the correct explanation of A
- both A and R are true and R is not the correct explanation of A
- assertion is false but reason is true
- assertion is true but reason is false
Assertion (A) : Longer wires have greater resistance and the smaller wires have lesser resistance.
Reason (R) : Resistance of a wire increases with increase in temperature.
- both A and R are true and R is the correct explanation of A
- both A and R are true and R is not the correct explanation of A
- assertion is false but reason is true
- assertion is true but reason is false
Two copper wires of equal length but different thickness are connected one by one to the same cell and bulb.
(a) In which wire will the rate of flow of the charge be greater? Give reason.
(b) Does a higher current mean that electrons move faster from the battery to the bulb?
(c) If current flows for a longer time, what happens to the charge passing per second? What happens to the total charge transferred?
A student connects a bulb to a cell using two wires, but the bulb does not glow. On checking, the bulb is found to be in proper condition. On further inspection, a wire is found to be loose.
(a) Why did the bulb not glow even though it was not faulty?
(b) What is meant by a closed circuit?
(c) Why is electric current considered as a flow of charges?
(d) What is the conventional direction of electric current?