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احضر نفسي لاختبار فيزياء بعد يومين وتوقفت عند بعض الأسئلة *اتمنى منكم مساعدتي في حلها..

A transformer has a coil of 5000 turns. When the output p.d is 12 v.. The input p.d is 240 v r.m.s
A- how many turns are there on the secondary coil?
B- the output from the secondary coil is connected across a 20 *lamp
- what is the r.m.s current in the secondary coil?
- what is the r.m.s current in the primary could ( assume the efficiency of the transformer is 100%)

أنا حليته كالتالي:
A- 12*5000= 240*Ns
= 240 turns
B-*
- 12\20 = 0.6 A
- 240 Ip=12*,6
= 0.03 A

هل أجابتي صحيحة؟

Q2
A step down transformer draws a current of .12 A from the 230 V mains supply. The transformers turns ratio is 1/20. Inefficiency reduces the secondary voltage to 95% of that which is expected
A- calculate the secondary voltage

The secondary voltage coul has a resistance if .50
The transformers load had a resistance of 6.5
Calculate
- the secondary current
- the power output
The efficiency

لم استطع حله*


Q3
A transformer designed to operate a 12 v lamp from a 240v supply has 1200 turns on the primary coil. Assuming that the transformer is 109% efficient. Calculate
- the number of turns on the secondary coil
- the current passing through the primary coil when the 12 v lamp has a current of 2 A flowing throgh it

- Ns*12=1200*240
=240 turns

- I = P/v
P=
12*2= 24w

هل الاجابة صحيحة؟

هل من مساعد؟؟

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