Physics Alternating Current Level: University
ImpedanceWhen the frequency of an ac circuit is increased at constant coltage the current increases and then decreases. Which combination of elements is most likly to comprise this circuit?
(a) Resistors only
(b) inductors only
(c) Capacitors only
(d) A combination of inductors and resistors
(e) A combination of inductors and capacitors
Physics Alternating Current Level: University
Reactancewhen the frequency of an ac circuit is decreased the current in the circuit increases. Which combination of elements is most likely to comprise the circuit?
(a) Resistors only
(b) Inductors only
(c) Capacitors only
(d) Capacitors and resistors
(e) Inductors and Capacitors
Physics Alternating Current Level: University
A battery is used to drive a circuit. After a certain amount of time the current is zero amperes. when the same circuit is drive by an ac generator the current is non-zero and alternates. which combination of elements is most likely to comprise the circuit?(a) resistors only
(b) Inductors only
(c) Capacitors only
(d) A combination of inductors and resistors
(e) A combination of inductors and capacitors
Physics Alternating Current Level: High School
Instantaneous Voltage
A time delay of 25 ms is required for the voltage to fall to 20 % of its maximum value . Rearrange the equation to find a new value of resistance to achieve this if the capacitance is kept the same .
Physics Alternating Current Level: High School
Instantaneous voltage
The instantaneous voltage in a capacitor circuit where v = Ve-t/cr . C is 2 microfarrad and f resistance R is 25 kilo ohms , V is 100 volts , and t is time , plot the function against time and from this find the voltage after 80 milliseconds . (Note : c and r is called time constant. ) After 5 CR the voltage will have settled . multiply 5 by C by R and plot to this time .
Physics Alternating Current Level: High School
The oscillator of a 98.1 MHz station has an inductance of 1.7 uH . What value must the capacitance be ?
Physics Alternating Current Level: High School
A transformer for a potable radio reduces 120 V ac to 9.0 V ac . The secondary coil contains 40 turns and the radio draws 350 ma . Calculate the current in the primary .
Physics Alternating Current Level: High School
A transformer for a potable radio reduces 120 V ac to 9.0 V ac . The secondary coil contains 40 turns and the radio draws 350 ma . Calculate the current in the primary .
Physics Alternating Current Level: High School
A chandelier with mass m is attached to the ceiling of a large concert hall by two cables . Because the ceiling is covered with intricate architectural decorations (not indicated in the figure, which uses a humbler depiction), ceiling directly above the chandelier . Instead , they attached the cable to the ceiling near the walls . Cable 1 has tension T1 and makes an angle of theta 1 with the ceiling . Cable 2 has tension T2 and makes an angle of theta 2 with the ceiling .
Find the expression for T1, the tension in cable 1, that does not depend on T2 .
Express your answer in terms of some or all of the variables m ,theta 1, and theta 2 as well as the magnitude of the acceleration due to gravity g .T1 = ?
Physics Alternating Current Level: High School
A crate weighing 550 N is dragged 20 m up a 60 degree incline . the change in the gravitational potential energy of the crate is ?
Physics Alternating Current Level: High School
Impulse
A 200 g ball hits a wall perpendicularly with a velocity of 30 m/s and rebounds back with a velocity of 20 m/s . If the collision lasts for 5 ms , find the average force exerted by the ball on the wall ?
Physics Alternating Current Level: High School
conservatoin of momentum
A 75 kg skater pushes on a 25 kg stationary object on the ice and gives it a velocity of 4.0 m/s find the recoil velocity of the skater .
Physics Alternating Current Level: High School
Mechanics
A 5.0 x 10^4 kg space probe is traveling at a speed of 11,000 m/s through deep space. Retrorockets are fired along the line of motion to reduce the probe’s speed. The retrorockets generate a force of 4.0 x 10^5 over a distance of 2500 km. What is the final speed of the probe?a. –3.38 x 10^3 J
b. zero J
c. 3.38 x 10^3 J
d. –345 J
e. 345 J
Physics Alternating Current Level: High School
LC Oscillator
An LC circuit is built with a 20.0 mH inductor and an 7.70 microfarrad capacitor . The current has its maximum value of 0.600 A at t = 0 s. How long is it until the capacitor is fully charged ? and what is the value across the capacitor at that time ?
Physics Alternating Current Level: High School
An ac voltage source that has a frequency f is connected across the terminals of a capacitor . Which one of the following statements correctly indicates the effect on the capacitive reactance when the frequency is increase to 4 f ?a) The capacitive reactance increases by a factor of four .
b) The capacitive reactance increases by a factor of eight .
c) The capacitive reactance is unchanged .
d) The capacitive reactance decreases by a factor of eight .
e) The capacitive reactance decreases by a factor of four .