# Rearranging and Solving Formulae

1. In a circuit containing a resistor and a capacitor, the instantaneous voltage V volts across the capacitor is given by the formula

Where R is the resistance in Ohms V is the initial voltage, C the capacitance in Farads and t is the time in seconds.

Determine the time at which the instantaneous voltage is 35 volts given that V = 160 volts, R = 15 KΩ and c = 15 ÂµF.

2. The power gain D decibels (dB) of an amplifier relates the input power P1 watts to the output power Po by the formula:

Determine the output power for a gain of 25 dB when the input power is 10 mW

3. Solve the equation 12.42p = 556.7 giving your answer correct to 2 decimal places.

4. Change the subject of each of the formula to that shown in Bold

Z = m(3 - exp( - Î±t)) Î±

u = we-pt p

y

Please see the attached file for the fully formatted problems.

https://brainmass.com/math/algebra/rearranging-solving-formulae-64249

#### Solution Summary

Formulae are rearranged and solved in the solution with details. The solution is detailed and well presented.