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प्रश्न
What is emf?
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उत्तर
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.).
संबंधित प्रश्न
Two lamps, one rated 40 W at 220 V and the other 60 W at 220 V, are connected in parallel to the electric supply at 220 V.
(a) Draw a circuit diagram to show the connections.
(b) Calculate the current drawn from the electric supply.
(c) Calculate the total energy consumed by the two lamps together when they operate for one hour.
In the network shown in the following adjacent Figure, calculate the equivalent resistance between the points.
- A and B
- A and C
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.
Find the effective resistance in the following circuit diagrams (Fig.):
An electric kettle has a heating element which is rated at 2 kW when connected to a 250 V electric supply. Calculate the
(a) Current which flows in the element when it is connected to a 250 V supply,
(b) Resistance of the filament,
(c) Heat produced in 1 minute by the element,
(d) Cost of running the kettle for 10 minutes a day for 30 days of the month, at the rate of Rs. 3.00 per unit.
The circuit diagram in fig shows two coils of an insulated copper wire wound on a cardboard tube. G is a center zero galvanometer.
(a) Describe what will happen when th e swi tch K is cl osed for severa l
seconds and then opened again .
(b) What will be the effect of repeating the experiment with an iron placed in the tube?
What should I choose ___________________
b. for getting protection from electric current.
c. to measure the current in the circuit?
