Home
Class 12
PHYSICS
A 200//120V step-down transformer of 90%...

A `200//120V` step-down transformer of 90% effciency is connected to an induction stove of resistance `40Omega.` Find the current drawn by the primary of the transformer.

Text Solution

Verified by Experts

`V_(p)=200,V_(s)=120V,eta=90%,R_(s)=40Omega,`
To find : `I_(p)=?`
Output power `V_(s)I_(s)" "[becauseI_(s)=V_(s)//R_(s)]`
`=(V_(s)^(2))/(R_(s))=(120xxcancel(120)^(cancel(30)))/(cancel(40))=360W.`
Formula : `eta=("Out put power")/("Inpur power")=(V_(s)I_(s))/(V_(p)I_(p))`
`V_(s)I_(s)=360`
`I_(s)=(360)/(120)=3A.`
`eta=(V_(s)I_(s))/(V_(p)V_(p))`
`(90)/(100)=(120xx3)/(200xxI_(p))`
`I_(s)=(12xx3xx100)/(90xx200)`
`I_(p)=2A`
Promotional Banner

Similar Questions

Explore conceptually related problems

A 220 volt input is supplied to a transformer.The output circuit draws a currnt of 2.0 ampere at 440 volts If the efficency of the transformer is 80% the current drawn by the primary windings of the transformer is :

A transformer has an efficiency of 80% and works at 100 V and 4 kW. The secondary voltage is 240 V. Calculate the current in the primary and secondary.

A capacitor of capacitance 8.0(mu)F is connected to a bettery of emf 6.0V through a resistance of 24(Omega) .Find the current in the circuit (a)just after the connections are made and (b)one time constant after the connections are made.

A battery of emf 2V and internal resistance 0.5(Omega) is connected across a resistance 9.5(Ω). Find the current flow through battery ?

A transformer is used to light a 140 W, 24 V bulb from a 240 V AC mains. The current in the main cable is 0.7 A. find the efficiency of the transformer.

A step down transformer convert a voltage of 2200 V into 220V in the transmission line. Number of turns in the primary coil is 5000. Efficiency of transformer is 90% and its output power is 8kW. Calculate (i) the number of turns in the secondary coil, (ii) input power.

A transformer connected to 220 V mains is used to light a lamp of rating 100 W and 110 V. If the primary current is 0.5 A, the effeciency of the transformer is (approximately)