Lesson 11
(1) The life-time of a 12V battery is 240 A-hr
(ampere-hour).
1.
How much charge can be battery deliver?
2.
How much energy?
3.
How long will it last if it delivers 2A of current constantly?

(2) The energy of a proton beam is 150MeV. Beam diameter is 5mm, beam current is 1.5mA. Find the beam density, assumed uniform.

(3) A 100  resistor is connected to a 12V ideal battery. Find
1.
the current
2.
the power dissipated
3.
the energy used up in 1 minute.

(4) Which has the higher resistance, a 1500W space heater W or a 100W light bulb?

(5) How much does it cost to operate a 1500W space heater for 8.0 hours, if the cost of electricity consumption is $0.2 per kWh?

(6) What is the length of a copper wire with circular cross-section of diameter 2.0mm and electrical resistance of 1.0mΩ? (Resistivity of copper =
1.72×10 -8 Ω-m)

(7) A coil is made by winding a copper wire on a cylindrical core of diameter 3.0cm. The diameter of the wire is 1.6mm. How many turns must be wound in order to produce a coil with resistance 2.0Ω?

(8) What happens to the resistance of a copper wire if both its length and its diameter are doubled?