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

Answer:

(a) Energy will be 675 J

(B) charge will be 450 C

(C) Total number of particles will be $281.25\times 10^6$

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 = $15\times 60=900sec$

(A) We know that energy is given by $E=P\times T=0.75\times 900=675j$

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

So $675=Q\times 1.5$

$Q=450C$

Now we have given charge on each particle $=1.6\times 10^{-6}C$

So number of charge particle $n=\frac{450}{1.6\times 10^{-6}}=281.25\times 10^6$