Question

a step down transformer is connected to main supply of 200 volt to operate a 6 volt 30 volt bulb the current in primary is


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Answer 1

The correct option (d) 0.15 A

 Explanation:

Current in secondary is

I2 = [(power)/(voltage)]

= [{30 w}/{6 V}]

= 5 A

also we know V1I1 = V2I2  

∴ I1 = [{V2I2} / {V1}]

given V1 = 200 V, V2 = 6 V & I2 = 5 A hence

I1   = [{6 × 5}/{200}]

= (3/20)

= 0.15 A.

Answer 2

Explanation:

$\sf\large\underline\purple{Given:-}$

$\displaystyle \sf \bigstar \: \: \: \: \small{ \rm{ \red{v1 = 200v}}} \\ \\ \displaystyle \sf \bigstar \: \: \: \: \small{ \rm{ \red{v2 = 6v}}} \: \: \: \:$

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$\sf\large\underline\purple{Used\:\:\:\: formulas:-}$

$\displaystyle \sf \bigstar \: \: \: \: \: \boxed{ \underline{ \boxed{ \bold{i = \frac{power}{voltage} }}}} \\ \\ \displaystyle \sf \bigstar \: \: \: \: \: \boxed{ \underline{ \boxed{ \bold{v1i1 = v2i2}}}}$

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$\sf\large\underline\purple{Solution:-}$

$\displaystyle \sf \bigstar \: current \: in \: secondary \: is \\ \\ \displaystyle \sf \bigstar i2 = \frac{30}{6} = 5a \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ \\ \displaystyle \sf \bigstar also \: we \: know \: that \: \: \: \: \: \: \\ \\ \displaystyle \sf \bigstar i1 = \frac{v2i2}{v1} \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ \displaystyle \sf \bigstar i1 \: = 0.15a \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \:$