Question

The primary and secondary coils of a transformer have $50$ and $1500$ turns respectively. If the magnetic flux $\varphi$ linked with the primary coil is given by $\varphi ={\varphi }_0+4t$, where $\varphi$ is in weber, t is time in seconds and ${\varphi }_0$ is a constant. The output voltage across the secondary coil is

• A. $90V$
• B. $6000V$
• C. $220V$
• D. $30V$

Answer 1

The correct option is B $6000V$

Equation of transformer:

$V_p=-N_p\frac{d\varphi }{dt}$

$V_s=-N_s\frac{d\varphi }{dt}$

And, $\frac{V_p}{V_s}=\frac{N_p}{N_s}$

Using:

$V_p=-N_p\frac{d\varphi }{dt}$

We get

$V_p=-50\times 4=-200$

Now let's use

$\frac{V_p}{V_s}=\frac{N_p}{N_s}$

$\Rightarrow V_s=6000V$