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SAT Physics 3

Question 1: Five particles charged with the same charge +q move with the same speed v in a magnetic field B, as shown above. Which particle experiences the highest magnetic force?

Question 2:
Two wires of circular cross-sectional areas have resistances R1 and R2.
If ρ1 = 2ρ2, l1 = 2l2 and r1 = 2r2, what is the ratio R1/R2?
ρ1, ρ2 are the resistivities of the two wires,
l1, l2 are the lengths of the two wires,
r1, r2 are the radii of the two wires.

Question 3: Two wires carry identical currents I, as shown above. At which point is the magnetic field the strongest?

Question 4: Two metallic bars slide along metallic rails at speeds v1 = .1m/s and v2 = .2m/s as shown above. The bar and the rails are situated in a magnetic field of 4T. What is the induced voltage in the bar and rails?

Question 5:
A police car with its siren on travels at a speed v1 toward a person. The frequency of the siren is f1 and the person hears the sound at a frequency f2. If vs is the speed of sound, v1 =

Question 6:
Violet light has a wavelength of 400nm. What is its frequency, if the speed of light is 3·108 m/s?

Question 7:
The activity of a radioactive sample at time t = 0s is A0 and the activity of the same radioactive sample at time t1 is A1. What is the decay constant of the sample?