A lamp has a rating of 18V 9W. How much energy is transferred to the bulb in 5 minutes? Calculate the current through it when connected to a 18V supply.
The first question comes from the realisation that the power rating, "9W" represents 9 joules being supplied every second and so can be written as 9J/s and so in 5 minutes (or 300 seconds) the energy supplied is:
9J/s * 300s = 2700J
The second part comes from the equation P=IV and we already have numbers for power and voltage:
9 = 18 * I
I = 9/18 = 0.5Amps
AN
Related Physics GCSE answers
All answers ▸Explain the different sources of background radiation
A ball of mass 500g is dropped from rest 2m above the ground. When it reaches the ground it is travelling at 5m/s. How much energy has been dissipated?
calaculate the resistance if two 3 ohm resitsors are placed in series and another 3 ohm was attached in parallel
Please describe the structure of atom, with reference to the relative mass and charge.