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Questions
What is emf?
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Solution
When no current is drawn from the cell, i.e., when the cell is in open circuit, the potential difference between the terminals of the cell is called its electromotive force (or e.m.f.).
RELATED QUESTIONS
What is the unit of electric current?
The figure given below shows an electric circuit in which current flows from a 6 V battery through two resistors.
- Are the resistors connected in series with each other or in parallel?
- For each resistors, state the p.d. across it.
- The current flowing from the battery is shared between the two resistors. Which resistor will have bigger share of the current?
- Calculate the effective resistance of the two resistors.
- Calculate the current that flows from the battery.
If the lamps are both the same in the figure given below and if A1 reads 0.50 A, what do A2, A3, A4 and A5 read?
The following circuit diagram shows three resistors 2 Ω, 4 Ω and R Ω connected to a battery of e.m.f 2V and internal resistance 3 Ω. If the main current of 0.25 A flows through the circuit, find:
- the p.d. across the 4 Ω resistors,
- the p.d. across the internal resistance of the cell,
- the p.d. across the R Ω or 2 Ω resistors, and
- the value of R.
A current of 0.3 A is flowing through a branch of 6 Ω resistors in a junction as shown in fig. . Calculate the
(a) P.d. across the junction XY,
(b) Current flowing through 9Ω and 24Ω
( c) P.d. across 24 Ω resistor, and
( d) e.m.f. of the cell.
Tick (✓) the correct choice among the following :
(a) A strong short bar magnet is dropped into a solenoid connected to a
galvanometer as shown in fig . The galvanometer shows a deflection to the left when the current in the coil as seen from above is counter clockwise. Which one of the following shows the correct deflection of the galvanometer when the magnet is at posi tions A, Band C.
Study the following circuit and find out:
(i) Current in 12 Ω resistor.
(ii) The difference in the readings of A1 and A2, if any.
State whether true or false. If false, correct the statement.
Current can produce magnetic field.
Assertion (A): Electric current will not flow between two charged bodies when connected if their charges are the same.
Reason (R): Current is the rate of flow of charge.
What is the rate at which charges flow past a point on a circuit?
