What is the phenomenon involved in the working of transformer ?

The phenomenon of mutual induction is involved in the working of transformer. NOTE: It is a device used to increase or decrease voltage in an alternating current circuit. It mainly consists of two coils wounded on the same core. The coil which is connected to input voltage is called primary coil and the coil which is connected to output is called secondary coil.The input and output voltage depends on the number of turns in primary and secondary coil respectively.

A power transmission line feeds input power at 2300 V to a stepdown transformer with its primary windings having 4000 turns. What should be the number of turns in the secondary windings in order to get output power at 230 V ?

Input Voltage, V 1 = 2300 V Number of turns in primary coil, n 1 = 4000 Output Voltage, V 2 = 230 V Say the number of turns in secondary coil is n 2 . Voltage is related to number of turns as, V 1 V 2 = n 1 n 2 ⇒ 2300 230 = 4000 n 2 n 2 = 4000 × 230 2300 = 400 Hence, there should be 400 turns in secondary windings.

E M B I B E

Intermediate Second Year Physics>Chapter 10 - Alternating Current>MODEL QUESTIONS (IPE PATTERN)>Q 8

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12th Andhra Pradesh Board

IMPORTANT

Earn 100

What is meant by wattless component of current ?

Important Questions on Alternating Current

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12th Andhra Pradesh Board

IMPORTANT

Intermediate Second Year Physics>Chapter 10 - Alternating Current>MODEL QUESTIONS (IPE PATTERN)>Q 9

When does a LCR series circuit have minimum impedance?

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12th Andhra Pradesh Board

IMPORTANT

Intermediate Second Year Physics>Chapter 10 - Alternating Current>MODEL QUESTIONS (IPE PATTERN)>Q 10

What is the phase difference between voltage and current when the power factor in LCR series circuit is unity?

HARD

12th Andhra Pradesh Board

IMPORTANT

Intermediate Second Year Physics>Chapter 10 - Alternating Current>MODEL QUESTIONS (IPE PATTERN)>Q 1

Obtain an expression for the current through an Inductor when an AC emf is applied.

HARD

12th Andhra Pradesh Board

IMPORTANT

Intermediate Second Year Physics>Chapter 10 - Alternating Current>MODEL QUESTIONS (IPE PATTERN)>Q 2

Obtain an expression for the current in a capacitor when an AC emf is applied.

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12th Andhra Pradesh Board

IMPORTANT

Intermediate Second Year Physics>Chapter 10 - Alternating Current>MODEL QUESTIONS (IPE PATTERN)>Q 3

State the principle on which a transformer works. Describe the working of a transformer with necessary theory.

HARD

12th Andhra Pradesh Board

IMPORTANT

Intermediate Second Year Physics>Chapter 10 - Alternating Current>MODEL QUESTIONS (IPE PATTERN)>Q 1

Obtain an expression for Impedance and current in series LCR circuit. Deduce an expression for the resonating frequency of an LCR series resonating circuit.

HARD

12th Andhra Pradesh Board

IMPORTANT

Intermediate Second Year Physics>Chapter 10 - Alternating Current>MODEL QUESTIONS (IPE PATTERN)>Q 1

An ideal inductor (no internal resistance for the coil) of $20 mH$ is connected in series with an AC ammeter to an AC source whose emf is given by $e = 20 \sqrt{2} \sin (200 t + π / 3) V$ , where t is in seconds. Find the reading of the ammeter (in Ampere).