The battery for a certain cell phone is rated at 3.70 V. According to the manufacturer it can produce 3.00×10^4J of electrical energy, enough for 7.20 h of operation, before needing to be recharged. Find the average current that this cell phone draws when turned on.

Explanation:

Given data

Voltage V=3.70V

time t=7.20h=25920s

Energy E=3.00×10⁴J

To find

Average current I

Solution

As we know that power is:

0.55x745.7j and a calculator

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27