Question

The resultant resistant two resistances 10 and 15 connected in of series, is _________​

Answer 1

Explanation:

Correct option is A)

R

eff

=10+15=25

⇒I=

25

1.5

=

50

3

=0.06A

=60mA

P.Dacross10=0.06×10

=0.6V

P.Dacross15=0.06×15

=0.9V

Answer 2

Resistance seen from power supply is R1= 20/1.5=13.333 ohms

Substracting 10 ohms resistor in serie R1-10= 3.333 ohms=Rp or parallels resistance.

the two 15 ohms in parallel gaves half resistance 7.5 ohms

Rp=7.5*R / (7.5+R) or (7.5+R)*Rp=7.5*R solving for R

7.5 *Rp=R*(7.5-Rp) or R=7.5*Rp/(7.5-Rp) replacing Rp=10/3

R=75/(22.5-10)=75/12.5=6 ohms