Download App

Electricity — PHYSICS STD 8 — Question

ICSE BoardEnglish MediumSTD 8PHYSICSElectricity3 Marks
Question
A source of potential difference $V$ volt sends current $I$ ampere in a circuit for time $t$ second. Write expressions for
$(1).$ electrical energy supplied by the source and
$(2).$ electrical power spent by the source.
✓

Answer

Potential difference $V$ is the work done in moving a unit charge
\therefore Work was done in moving a charge Q through the pot. diff. $V = QV$
i.e. $W = QV$
but $=\frac{Q}{t}= I$ or $Q= It$
Work done $=$ Electrical energy
$(a) \therefore$ Electrical energy $= VIt$ is the expression
$(b)$ Power is the rate of doing $W$
$P=\frac{W}{t}=\frac{V I t}{t}=V I$
$P = VI$ is the expression.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "[3 Mark Question Answer]" from Electricity→Electricity — all question types→PHYSICS STD 8 question papers→ICSE Board STD 8 question papers→ICSE Board question paper generator→

Similar questions

State the colour coding of the three wires in a cable used for
→
Write the expression for work done by a force.
→
The potential energy of a body of mass $0.5 \ kg$ increases by $100 J$ when it is taken to the top of a tower from ground. If force of gravity on $1 \ kg$ is $10 N$, what is the height of the tower?
→
Describe Franklin’s experiment. What did he conclude from his experiment?
→
A straight stick partly dipped in water obliquely, appears to be bent at the surface of water.
→
Draw a ray diagram to show the formation of the image of an object placed beyond the centre of curvature of a concave mirror. State the position, size and nature of the image.
→
Explain in brief why birds that walk on the leaves floating on the surface of water have wide feet.
→
If the magnitude of force acting on a surface is doubled and area over which it acts is halved, then what will be the effect on pressure ?
→
In figure $AO$ is the ray of white light falling on a prism $\text{PQR}$. Complete the diagram till the light emerges out from the prism and falls on the screen.
→
Calculate the pressure exerted on a surface of $0.5\ m^2$ by a thrust of $100\  kgf.$
→