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What is the resistance (in Ohms) of two 20 Ohm resisters in parallel?

1/20 + 1/20 = 1/R2/20 = 1/R1/10 = 1/RR = 10 Now, answer for a 20 Ohm and a 10 Ohm resister in parallel?1/20 + 1/10 = 1/R3/20 = 1/RR = 6.67 Ohm
TD
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Two current carrying wires are placed next to each other and anti-parallel currents are allowed to flow. Is the magnetic force between the wires attractive or repulsive?

Consider the first wire on the left with current running up (arbitrary choice). By the 1st right hand rule, the magnetic field anywhere on the right will be into the page. By the 2nd right hand rule, the for...
Answered by • Physics tutor
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A bowling ball is thrown into the alley, having velocity of 3 ms^-1 at the start of the bowling alley. It decelerates at a constant rate, before hitting the skittles at 2 ms^-1 after 4 s A) calculate the acceleration of the ball.

A) acceleration (m/s2) = change in velocity (m/s) / time (s) A) -1.0 ms -1 / 4 s = -0.25 ms -2 B) Calculate the displacement the ball travelled before hitting the skittles and hence calculate the average vel...
AN
Answered by Alexander N. • Physics tutor
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I never know where to start where I get a calculation question given many values, what should I do? (e.g: finding how much energy is needed for all the ice in a glass of water to melt after the ice is dropped into warm water)

Firstly, you should always list down the values that were given to you in the question so that you know exactly what you already know, and then by looking at this list, it makes it easier for you to remember...
SL
Answered by Simone L. • Physics tutor
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This is a question on the photoelectric effect: For potassium, the work function is 3.65E-19J. Find the maximum wavelength of light that will cause photoelectrons to be emitted when shone onto potassium.

We know thatphoton energy = minimum energy needed to free an electron + max kinetic energy of emitted photoelectronAs we have been asked for the maximum wavelength , we know these photoelectrons just have en...
KB
Answered by kathryn b. • Physics tutor
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