Physics Answers

Our speakers use 200 mA of current at maximum volume. The voltage is 12V. The current is used to produce a magnet which is used to move the speaker cone. Find the resistance of the electromagnet.

What is the electric potential 15.0 cm from a point charge?

(a) Calculate the capacitance of a parallel-plate capacitor whose plates are 20 cm x 30 cm and are separated by a 1.0-mm air gap.

(b) what is the charge on each plate if a 12-V battery is connected across the two plates?

(c) What is the electric field between the plates?

A student walks 625m west and 475m north, calculate the distance of the student walk. Calculate the displacement of student walking west.

Calculate the displacement of student walking north

a block of 18kg is pushed along a horizontal frictionless surface by a horizontal force of 80N. the block start from rest. compute the kinetic energy after 6 seconds

. A rigid tank contains 10 𝑘𝑔 of water at 90𝑜 𝐶. If 8 𝑘𝑔 of the water is in the liquid form

and the rest is in vapour form, determine:

i. the pressure in the tank,

ii. the volume of the tank.

Physics Drill: Ohm’s Law. Solve the problem using the principles of Ohm’s

Law below. Show your complete solution.

1. Find the current through a resistor of resistance 𝑅 = 2Ω if the voltage across

the resistor is 6V.

2. While repairing an electric bulb socket, an electrician gets a mild shock when a

current of 0.0050 A passes through him. The same electrician was killed by a

current of 0.15 A when he turned on an electric bulb while taking a bath. The

voltage in each situation is equal to 120 V. Find the resistance of the electrician

in each situation.

3. A typical value of the resistance of a person from hand to hand through the

body is 2,000 Ω. If a person with this resistance accidentally touches a 220 V

live wire, what current passes through the person?

Physics Drill: Voltage Solve the problems about Voltage below. Show your

complete solutions.

1. It takes 20 J of work to push 4C of charge across the filament of a bulb. Find

the potential difference across the filament.2. The potential difference between two terminals of a cell is 3V. Find the Work

done in moving 5C of charge across the cell.

3. A group of electrons of net magnitude of charge, 𝑄 = 0.50 𝐶, passes through a

cell of voltage, 𝑉𝑐𝑒𝑙𝑙 = 20𝑉, from the (+) to the (-) terminal. What is the change

in energy, ∆𝐸, of the group of electrons as they move across the terminals?

Physics Drill: Electric Current. Fill in the missing information by solving for

the problem about electric current below:1. If the current in a wire is one ampere, then ___ coulomb(s) of charge flows past a

point in the wire every ____ second(s).

2. When 8 coulombs of charge flow past a point in a circuit in 2 seconds, the current

is ______.

3. If the current at appoint in a circuit is 1.5 A, then ____ of charge flow past this point

every second.

4. If the current at a point in a circuit is 0.75 A, then ___ of charge flow past this point

every 5 seconds.

5. If the current in the wire is 0.80 A, then it takes ___ seconds for 2.4 C of charge to

flow past this point in the wire

1.     A stone is thrown vertically upward from ground level. Six seconds later, a second stone is also thrown vertically upward from the same point with a velocity of 40 m/sec. If the two stones meet 30 meters above the ground with the first stone already going down, with what velocity was the first stone thrown?