Posted by **Charles** on Tuesday, April 17, 2007 at 3:24am.

Please can you help out:

1)The Potential diff across the terminals of a battery is 8.5v when there is a current of 3amps in the cct from the -ve to the +ve terminal. When the current is 2amps in the reverse direction, the potential diff becomes 11volts.

a) what is the internal resistance of the battery?

b) what is the e.m.f of the battery

2) The instantaneous current I across a 200-ohm resistor is given by I= 10cos 377t

a) find the freq and the period

b) find the voltage across the resistor when t=1/240 second

At 3 amp,

8.5=emf =3r

at 2 amp

11 = emf=2r

you have two equations, two unknowns. Solve for emf and r. You can solve for rinternal directly by subtracting the equations.

On the second, frequency is in the given. remember Amplitude*cos(2PI*f*t) is the wave formula.

## Answer this Question

## Related Questions

- physics - when you connect an unknown resistor across the terminals of a 1.50 V...
- physics - The emf of a battery is equal to its terminal potential difference: A...
- Physics - A battery charger is connected to a dead battery and delivers a ...
- Physics - A battery with an emf of 10.3 V and internal resistance of 1.03 Ω...
- physics - Consider a battery that has Vt = 12.0 V when it is not connected to a ...
- Physics - A battery has an internal resistance of 0.42. A number of identical ...
- physics (please check) - Four 20-ohm resistors are connected in series and the ...
- physics - The voltage across the terminals of a 8.90 V battery is 8.00 V when ...
- Physics - 1)A 2.0-V battery is connected in a circuit with an ammeter and an ...
- Physics - By our sign conventions, if a battery is traversed in the actual ...

More Related Questions