ICSE physics
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Question
A 900 pF capacitor is charged by a 100V battery. How much energy is stored by the capacitor ?
Solution
C = 900 PF = 900 x 10-12 F
V = 100V
Energy stored in the capacitor is given by,
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Question
An AC voltage of 200 V is applied to the primary of a transformer and a voltage of 2000 V is obtained from the secondary. Calculate the ratio of current passing through the primary to that in the secondary coil.
Solution
EP = 200 V, Es = 2000 V
Question
If the temperature of the cold junction of a thermocouple is lowered, what will be the effect on its neutral temperature and temperature of inversion ?
Solution
Neutral temperature is independent of temp. of cold junction, hence neutral temp, will not change, if temp, of cold junction is lowered.
T, = 2 Tn T0
If temp. of cold junction decreases, temperature of inversion increases.
Question
A charge of 5C is placed at the centre of a circle of radius 10 cm as shown in the figure below. Calculate the work done in moving a charge of 2C from point A to B on the circumference of the circle.
Solution
Electric potential, 
Potential is the same at each point because it is an equipotential surface.
VA = VB
Therefore,
WA to B = 0
That is, work done in moving a charge of 2C from point A to B.
Question
A 2V battery with internal resistance of 0.1 Ω is charged with a current of 5A. Calculate the potential difference between the terminals of the battery.
Solution
Electric potential, V = 2 V
r = 0.1 Ω, i = 5A
V = E + ir
= 2 + 5 x 0.1
V = 2.5 volt
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Mock Test Series
Mock Test Series