# science

posted by .

there are three sources of resistance in a parallel ciruit. Two of them are rated at 20ohms, the other at ohms. What is the curuit's total resistance? A)20 ohms B)12 ohms C)8 ohms D)5 ohms

• science -

letter B

• science -

You haven't stated the third resistance, but both A) and B) are not possible for any value in parallel with two 20 ohm resistors. The only possible answers are C) and D).

using 1/R(total) = 1/R +1/R +1/R

1/20 +1/20 =0.1

if the unstated value =x

A)

so 0.1 +1/x = 1/20 = 0.05
which requires a -ve value for x

B)

so 0.1 + 1/x = 1/12 = 0.0833
which requires a -ve value for x

C)

so 0.1 + 1/x = 1/8 = 0.125
which requires a value for x=40 ohms

D)

so 0.1 + 1/x = 1/5 = 0.2
which requires a value for x=10 ohms

## Similar Questions

1. ### science

Calculate the resistance in a circuit in which a 9-volt battery produces 3 amperes. A)3 ohms B)6 ohms C)9 ohms D)27 ohms
2. ### Physical Science

Hello, Can someone tell me if I have the correct answer?
3. ### SCIENCE

THERE ARE THREE SOURCES OF RESISTANCE IN A PARALLEL CIRCUIT,S . TWO OF THEM ARE RATED AT 20 OHMS THE OTHER AT 10 OHMS WHAT IS THE CIRCUIT,S TOTAL RESISTANCE.
4. ### Science

There Are Three Resistance In A Parallel Circuit. Two Of Them Are Rated At 20 Ohms, The Other At 10 Ohms. What Is The Circuit's Total Resistance?
5. ### physics

A 15.0 Ohms resistor is connected in series to a 120V generator and two 10.0 Ohms resistors that are connected in parallel to each other. -What is the total resistance of the load?
6. ### science

There are three sources of resistance in a parallel circuit. Two of them are rated at 20 ohms, the other at 10 ohms. What is the circuits total resistance?
7. ### Algebra 2

two resistors are connected in parallel. Their resistances are 6 ohms and 10 ohms. What is the resistance, (R), of the combination?
8. ### Algebra 2

two resistors are connected in parallel. Their resistances are 8 ohms and 17 ohms. What is the resistance (R) of the combination?
9. ### science

according to ohms law what is the resistance of a lightbulb if that applied voltage is 21.0 V and the current is 3.0 amps?
10. ### Science

Use Ohmâ€™s Law to determine the resistance in a circuit if the voltage is 12.0 volts and the current is 4.0 amps. A.8.0 ohms B. 48 ohms C.3.0 ohms** D.12 ohms

More Similar Questions