# physics

posted by .

A 24V battery of internal resistance of 10ohms is connected to a variable resistor. At what value of current drawn from battery the rate of heat produced by the resistor is maximum? Hence find its value.

• physics -

Delivered power is a maximum when the internal and external resistances are equal, as I recall. Therefore
Rexternal(optimum) = 10 ohms.
Current with that external resistance
= V/Rtotal = 24/20 = 1.2 Amps

Maximum power produced in external resistor =
I^2*Rexternal = (1.2)^2 * 10 = 14.40 W

Check: If I use Rexternal = 11 ohms instead, Rtotal = 21 ohms and I = (24/21) = 1.143 A
I^2 * Rext = 14.37 W

If you use Rexternal = 9 ohms, your will still get a power less than 14.4 W

## Similar Questions

1. ### Physics

Batteries are not perfect. Instead they have an "internal resistance, a catch all phrase which describes the internal chemical workings of the battery which prevents it from providing an unchanging voltage regardless ofnits load. A …
2. ### Physics

Batteries are not perfect. Instead they have an "internal resistance, a catch all phrase which describes the internal chemical workings of the battery which prevents it from providing an unchanging voltage regardless ofnits load. A …
3. ### physics

when you connect an unknown resistor across the terminals of a 1.50 V AAA battery having a negligible internal resistance, you measure a current of 18.0 mA flowing through it .A)what is the resistance of the resistor. B) if you now …
4. ### physical

A battery of e.m.f 24v and internal resistance of 4ohms is connected to a resistor of 3ohms.what is the terminal potential difference of the battery
5. ### physics

Consider a battery that has Vt = 12.0 V when it is not connected to a circuit. When a 10.0- resistor is connected with the battery, the potential difference across the battery’s terminals drops to 10.9 V. What is the internal …
6. ### Physics

A 79.4-Ω and a 47.7-Ω resistor are connected in parallel. When this combination is connected across a battery, the current delivered by the battery is 0.296 A. When the 47.7-Ω resistor is disconnected, the current from …
7. ### physics

A 6.0 Ù resistor and a 3.0 Ù resistor are connected in parallel to a 1.5 V battery of negligible internal resistance. What is the current in the 3.0 Ù resistor?
8. ### science

A 24 V battery of internal resistance 4 ohm is connected to a variable resistor. At what value of the current drawn from the battery is the rate of heat produced in the resistor is maximum?
9. ### physics

when a battery is connected to a 100-Ω resistor, the current is 4.00 A. When the same battery is connected to a 449-Ω resistor, the current is 1.09 A. Find the emf supplied by the battery and the internal resistance of the …
10. ### physics

hen a battery is connected to a 100-Ω resistor, the current is 4.00 A. When the same battery is connected to a 449-Ω resistor, the current is 1.09 A. Find the emf supplied by the battery and the internal resistance of the …

More Similar Questions