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ICSE Class 10 Physics Question 14 of 20

Electro-magnetism — Question 3

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Question

Question 3

A transformer is designed to give a supply of 8 V to ring a house bell from the 240 V a.c mains. The primary coil has 4800 turns. How many turns will be in the secondary coil?

Answer

Given,

Es = 8 V

Ep = 240 V

Np = 4800

Ns = ?

We know that,

Now,

EsEp=NsNp\dfrac{E_s}{E_p} = \dfrac{N_s}{N_p}

Substituting the values in the formula we get,

8240=Ns4800⇒Ns=4800×8240⇒Ns=160\dfrac{8}{240} = \dfrac{N_s}{4800} \\[0.5em] \Rightarrow N_s = 4800 \times \dfrac{8}{240} \\[0.5em] \Rightarrow N_s = 160 \\[0.5em]

Hence, the number of turns in the secondary coil = 160