Electric Circuits Answers

1. A 25 Ω resistor and a 35 Ω  resistor are connected in series and placed across a 120 V source.  (a)  Determine the effective resistance of the circuit.  (b)  What is the current in the circuit?  (c)  What is the voltage drops across the 25 Ω resistor?  (d)  What is the power used in the 35 Ω resistor?

A straight conductor with length 10.0 m passes through a uniform magnetic field 0.75 m wide. The current in the conductor is 2.0 A directed east, and the magnetic field is 0.60 T [down]. Find the magnetic force on the conductor, including direction.

Two charges are located on the positive X-axis of a

coordinate system. If and are 5cm

and 7cm from the origin (X=0). What is the force

exerted by & on a third charge ; if

A. is placed at 3cm from the origin?

watches TV on Saturday after her modular class on weekdays. if the TV has 400 watts and used it for 8 hours, how much does it cost if electricity is ₱6.88 per kWh? convert: 400 W= 0.400 kilowatts

a poster promoting electrical safety in households.

Our body is a moderately good conductor of electricity. Taken as a whole, our body’s resistance measured for conduction from the fingers of one hand to the other is about 1500 ohms when dry and 500 ohms when wet. The electric potential at a wall socket is 220 V, so if we inadvertently touch a high potential house with one hand, what will be the current trough our body when (a) dry and (b) wet. (c) Using the chart below, what do you think will happen to us if there are such amounts of current passing through our body?

2.8 Connect the same resistors in parallel. (a) Make a schematic diagram. Then, find (b)

the current and voltage in each load and (c) the total Current, Resistance and Voltage in the circuit.

Resistance

Current

Voltage

𝑅1

3kΩ

𝟓 𝒙 𝟏𝟎−𝟒𝑨

1.5 V

𝑅2

10 kΩ

𝟓 𝒙 𝟏𝟎−𝟒𝑨

5V

𝑅3

5kΩ

𝟓 𝒙 𝟏𝟎−𝟒𝑨

2.5 V

Total

18 kΩ

𝟓 𝒙 𝟏𝟎−𝟒𝑨

2.7 Find the power dissipated in the following resistors

1. 100kΩ resistor with a 10A of current
2. 45Ω resistor with a 25mA of current
3. 1kΩ resistor with a 75mA of current

A 20 meter length of cable has a cross-sectional area of 1mm2 and a resistance of 5 ohms. Calculate the conductivity of the cable. 𝜎 = 4𝑥106𝑠𝑖𝑒𝑚𝑒𝑛𝑠

What will be the conductivity of the cable if its length is (a) reduced by 1⁄4 of its original length (b) doubled?