Question

How many 117ohm resistor are required to Carry 5A on 220v line.​

Answer 1

Explanation:

Given: Individual resistance, R=176 Ω

I=5 A

V=220 V

Let number of resistors be n.

Then, R

1

=R

2

=......=R

n

=R=176 Ω............(i)

For resistors in parallel,

R

eq

1

=

R

1

1

+

R

2

1

+.....

R

n

1

..........(ii)

From (i) and (ii),

R

eq

=176/n...........(iii)

By ohm's Law,

V=IR

eq

220=5R

eq

...............(iv)

Substituting (iii) in (iv),

220=5×176/n

n=4