Question

how many 156 ohm resistors are required to get 15 a on 180 v when connected in parallel combination​

Answer 1

Answer:

13 resistors

Explanation:

Given:

• Resistance of the resistors = 156 ohms
• Current to be obtained = 15 Amperes
• Voltage supplied = 180 Volts

To find:

• No. of resistors

When any number of resistors of same resistance are connected in parallel:

$Req = \dfrac{Resistance}{Number \ of \ resistors}$

Let number of resistors be equal to X

Req = $\dfrac{156}{X}$

V=IR

180= 15 × $\frac{156}{X}$

180 = $\dfrac{2340}{X}$

180X=2340

X = $\dfrac{2340}{180}$

X = 13 resistors

13 resistors must be connected

Answer 2

Question :-

How many 156 ohm resistors are required to get a 15 A (current) on 180 V (potential difference) when connected in parallel combination ?

Solution :-

required current, I = 15 A

potential difference, V = 180 V

so,

Required resistance = V / I

required resistance, R_(eq)= 180/15 =12 Ω

Now,

Let, no. of resistors required = n

we know formula

$\blue{\bf{\frac{1}{R_{eq}}=\frac{1}{R_1}+\frac{1}{R_2}+...+\frac{1}{R_n}}}$

here,

All resistances are equal to 156 ohms

therefore,

$\bf{\frac{1}{12}=n\times\frac{1}{156}}$

$\bf{n=\frac{156}{12}=13}$

Hence, 13 resistors are required .