Question

You have a flashlight that uses 0.75 watts of power and requires 1.5 volt battery.How many joules of energy are used by the flashlight in 15 minutes? Hint: Joules are watts and seconds and you are computing the difference between the electric energy at two points A and B.What the total charge q0? Hint: the statement of the problem provides delta V.How many particles, each having a charge of 1.60 x 10^-6, are needed to produce the total charge at q0?

Answer 1

(a) Energy will be 675 J

(B) charge will be 450 C

(C) Total number of particles will be
`281.25* 10^6`

Step-by-step explanation:

We have given that a flashlight uses 0.75 watts of power

So power P = 0.75 watt

Voltage is given as V = 1.5 volt

Time is given as t = 15 minutes

We know that 1 minute = 60 sec

So 15 minutes =
`15* 60=900sec`

(A) We know that energy is given by
`E=P* T=0.75* 900=675j`

(b) We know that energy is also given by
`E=QV`

So
`675=Q* 1.5`

`Q=450C`

Now we have given charge on each particle
`=1.6* 10^(-6)C`

So number of charge particle
`n=(450)/(1.6* 10^(-6))=281.25* 10^6`