Plz help asap. 1. Describe the methods by which an electric potential develops in primary cells and dry cells.
2. Describe the methods by which an electric potential develops in generators and thermocouples.
3. Identify the scenarios below as to whether they would increase or decrease the resistance of an electric current through a body.

a. Increase the length of the conductor
b. Utilize a conductor with a larger cross-section
c. Cool the conductor to lower its temperature

4. If 0.8 Wh of electrical energy is lost as heat, how much heat energy (in Btu) is produced?
5. How many kilowatt-hours of energy would be used by a 40 W bulb that runs for 10 hours every day during the course of one year?

Not my answer but nevertheless

Electric potential develops in primary/dry cells through a chemical reaction between the cell plates of the cell. free electrons move from the zinc plate to the copper plate through a conducting material.  

Electric potential develops in Generators via magnetic induction i.e. the movement of a conducting rod through the magnetic field between the poles of the horseshoe magnets produces Electric potential in Generators.

Electric potential develops in thermocouples via heat transfer ; A heat source is applied to the connecting end of the thermocouple strips and this will cause the production electric charges ( potential ) at the free ends

3) Identifying effect of each scenerio

a) The resistance of an electric current will increase when the length of the conductor increases

b) The resistance of an electric current through a body will decrease when the conductor has a larger cross-section

c) The resistance of an electric current through a body will decrease when the temperature of the conductor is cooled

4) The amount of heat lost as heat in Btu = 2.73 Btu

amount of heat lost = 0.8 Wh

convert to Btu = 0.8 Wh / 0.293 = 2.73 Btu   ( note : 1 Btu = 0.293 Wh )

5) The amount of of energy used by a 40 W bulb for 365 days = 146 kWh

Power of bulb = 40 W

Run time = 10 hours * 365 days

∴ amount of energy used = 3650 * 40 = 146 * 10^3 Wh = 146 kWh

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation:

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