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Physics - Electricity and Magnetism - Problems with Solutions and Tutorials

electromag
Two electrons are 1 Angstrom apart. What is the repulsive force between them?

Answer: F = 2.3083086785009856e-8 N

Solver Input: q1=-1e,q2=-1e,r=1Angstrom,F=?

Tutorial video:
electromag
Two identical charges, separated by a distance of 1cm in water (dielectric constant = 80), experiences a repulsive force of 0.01 N. What is the magnitude of the charges?

Answer: q1 = 9.43438210181672e-8 C

Solver Input: r=1cm,K=80,F=0.01,q1=?,q2=?

Tutorial video:
electromag
An electron circles a proton at a radius of 0.5 Angstrom. What is the speed of orbit?

Answer: v = 2251217 m/s

Solver Input: q1=1e,q2=-1e,r=.5Angstrom,v=?

Tutorial video:
electromag
A proton starts off with a velocity of 14000 m/s and travels from one plate of a capacitor to the other. What is its final velocity if it goes from the (+) plate to the (-) plate? Note: the capacitor produces an electric field of 1 N/C over a distance of 1 m.

What about if it goes from the (-) plate to the (+) plate?


Answer: 19696 if along E, 2019 if against E

Solver Input: q=+e,vi=14000,vf=?,E=1,d=1

Tutorial video:
electromag
Ignoring relativity, what is the potential drop needed to accelerate an electron from rest to the speed of light (3e8 m/s)?

Answer: 255791

Solver Input: dV=?,q=-e,vi=0,vf=3e8

Tutorial video:
electromag
Charge one is +2 Coulombs, charge two is +3 Coulombs. They are 4 meters apart. How much work does it take to bring them together to 1 meter from each other?

Answer: 40446000000 J

Solver Input: q1=2,q2=3,ri=4,W=?,rf=1

Tutorial video:
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electromag
Find the absolute potential experienced by X, 1 mile from a Coulomb of charge.

X can be anything: a test charge, or a real charge. It doesn't matter what's experiencing it. The absolute potential depends only on the charge that's producing it.


Answer: 5584883

Solver Input: V=?,d=1mi,q=1

Tutorial video:
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electromag
A capacitor has a capacitance of 9e-8 Farad. The plates are 1 meter apart, and the dielectric in between them has a K = 82.67. What is the area of the plates?

Answer: 123 m^2

Solver Input: C=9e-8,d=1,K=82.67,A=?

Tutorial video:
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electromag
A circuit has a voltage of 5 V, a resistance of 3 ohms. How long does it take for 1 Coulomb of charge to pass through a point in the circuit?

Answer: t = 0.6 s

Solver Input: V=5,R=3,t=?,q=1

Tutorial video:
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electromag
Copper has a resistivity of 1.68e-8 ohm*m. A typical electronics wire has a cross section area of 1 mm^2. How long must this wire be in order to cause a resistance of 1 ohm?

Answer: L = 59.5 m

Solver Input: rho=1.68e-8,A=1mm^2,L=?,R=1

Tutorial video:
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electromag
120 Coulomb of charge pass through a resistor every minute. The voltage across the resistor is 0.5 V. What's the power of the resistor?

Answer: P = 1 W

Solver Input: q=120,t=1min,V=.5,P=?

Tutorial video:
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electromag
A line delivers 15 kW of power with a total resistance of 0.2 ohm. What voltage must the line be at in order to have an efficiency of 96%? At this voltage, what is the I2R power loss?

Answer: V = 268.32815729997475 V, I2R_loss = 625 W

Solver Input: P_delivered=15kW,R=.2,V=?,eff=.96,I2R_loss=?

Tutorial video:
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electromag
A proton moves through a magnetic field of 3 Tesla at 4.7e5 m/s. If the angle between the velocity and the field is 30 degrees, what is the force on the proton?

Answer: F = 1.127986593019159e-13 N

Solver Input: q=e,B=3,v=4.7e5,theta_v_B=30,F=?

Tutorial video:
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electromag
A magnetic field points into the page. Under its influence, an electron circles in the plane of the page with a speed of 3e5 m/s and at a radius of 3 Angstroms. Calculate the strength of the magnetic field.

Answer: B = 5684.254293120608 T

Solver Input: q=-e,v=3e5,r=3Angstrom,B=?

Tutorial video:
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electromag
20cm wire experiences a force of 1 N inside a magnetic field of 1 Tesla. If the angle between the current (wire) and the field is 45 degrees, what must be the current in the wire?

Answer: I = 7.071067811865476 A

Solver Input: L=20cm,F=1,B=1,theta_I_B=45,I=?

Tutorial video:
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electromag
A 50 coil rectangular loop with a width of 5cm and length of 8cm carries a current of 1 A, and is subjected to a magnetic field of 1 Tesla. If the angle of the area to the field is 10 degrees, what is the torque experienced by the loop?

Answer: tau = 0.0347 N*m

Solver Input: N=50,A=5*8cm^2,I=1,B=1,theta_A_B=10,tau=?

Tutorial video:
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electromag
A railgun as shown, is subjected to a magnetic field of 0.2 Tesla, a resistance of 2 ohm, and a current of 2 A. The length of the projectile is 20cm, what is the speed of the projectile?

Answer: v = 100 m/s

Solver Input: B=.2,R=2,I=2,L=20cm,v=?

Tutorial video:
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