Advertisements
Advertisements
Question
A 200V/120V step-down transformer of 90% efficiency is connected to an induction stove of resistance 40 Ω. Find the current drawn by the primary of the transformer.
Advertisements
Solution
Given data:
Vp = 200 V
Vs = 120 V
η = 90% = `90/100` = 0.9
`η = "output power"/"input power"`
`therefore 0.9 = ("V"_"S""I"_"S")/("V"_"p""I"_"p")`
`therefore "V"_"S" = "I"_"S""R"_"S"`
`"I"_"S" = "V"_"S"/"R"_"S" = 120/40` = 3A
∴ 0.9 = `(120 xx 3)/(200 xx "I"_"p")`
`"I"_"p" = (120 xx 3)/(200 xx 0.9) = (120 xx 3)/(20 xx 9)`
`"I"_"p"` = 2 A
APPEARS IN
RELATED QUESTIONS
State the principle on which transformer works.
Explain the construction and working of the transformer.
The following diagram in Fig.10.42 shows a coil of several turns of copper wire connected to a sensitive centre zero galvanometer G near a magnet NS. The coil is free to move in the direction shown in the diagram.
(i) Describe the observation if the coil is rapidly moved.
(ii) How would the observation be altered if (a) the coil has twice as many turns (b the coil was made to move three times as fast?
Why is the core of a transformer made of soft iron?
A transformer lowers e.m.f. from 220 V to 15 V. If 400 W power is given in primary, calculate (i) the current in primary coil and (ii) the current in secondary coil.
A transformer lowers e.m.f. from 220 V to 15 V. If the number of turns in primary are 3520, how many turns are in the secondary coil?
In a transformer, the number of turns in the primary and the secondary are 410 and 1230 respectively. If the current in primary is 6A, then that in the secondary coil is
Find out the phase relationship between voltage and current in a pure inductive circuit.
The primary coil of a transformer has 60 turns whereas its secondary coil has 3000 turns.
If a current of 5A flows in the primary coil, how much current will flow in a load in the secondary coil? State the assumption you have made regarding the transformer, in this calculation.
A 12 V, 60 W lamp is connected to a 220 V AC supply using an ideal transformer. Find the primary current.
