1. A time varying magnetic flux through a closed loop of wire induces a voltage
ID: 2302972 • Letter: 1
Question
1. A time varying magnetic flux through a closed loop of wire induces a voltage within that loop. (a) True (b) False
2. A circular loop of copper wire is lying flat on a horizontal table. A bar magnet is held with its south pole downward vertically above the center of the coil. The magnet is released from rest and falls toward the coil. As viewed from above, as it falls, the magnet induces (a) a counter-clockwise current in the loop (b) clockwise current in the loop (c) no current in the loop
3. A device that transforms mechanical energy into electrical energy is a
a. generator b. motor c. transformer
4. Neon signs require about 12,000 volts (output voltage) to operate. The "step up" transformer to boost voltage for the bright lights uses a 120-Volt (input voltage) source. What is the ratio of primary to secondary turns on the transformer? a. 1/100 b. 100/1 c. nota
5. A resistor R and inductor L in series are connected across the terminals of a battery at constant voltage. After the switch is closed to complete the LR circuit, the current I increases non-linearly with time until maximum current is reached. True or False .
(a) True (b) False
6. A curious high school physics student tries out a crude generator by laying a movable conducting rod on a U shaped conductor IN THE PLANE OF THIS PAGE. In this setup, a uniform magnetic field is perpendicular TO THE PAGE AND to the area bounded by the U shaped conductor and moving rod. The U shaped conductor and moving rod create a closed conducting path for current. The length of the moving rod and width of U shaped conductor is L = 15.0 cm. The student pulls the rod to the right at speed v = 20.0 cm/s. The magnetic field has magnitude B = 0.800 T and points IN.
What direction does the current flow in the closed conducting path? (a) clockwise (b) counterclockwise
7. In the previous problem, what is the magnitude of the induced voltage (emf) between the ends of the rod?
(a) 24 (V) (b) 2.4 (V) (c) 0 (V) (d) nota
8. In order to double the natural frequency of an LC circuit, you could:
(a) double both the inductance and capacitance
(b) reduce by one-half both the inductance and capacitance
(c ) nota
9 . In order to double the resonant frequency of an R-L-C ac circuit, you could:
(a) double both the inductance and capacitance
(b) reduce by one-half both the inductance and capacitance
(c ) double the resistance .
(d) cut the resistance in half
10. For the current to have its maximum value in a series R-L-C ac circuit,
the angular frequency is equal to (a) zero (b) infinity (c) the square root of 1/(LC).
11. In a series R?L?C ac circuit at resonance,
(a) the impedance is zero.
(b) the impedance has its maximum value.
(c) the total impedance has its minimum value, which is equal to R.
12. A circuit consists of a light bulb, a capacitor, and an inductor connected in series to an ac power source. The capacitor and the inductor have equal reactances. If both the capacitor and the inductor are removed from the circuit, what will happen to the brightness of the light bulb?
(a) it will increase (b) it will decrease (c) it will remain the same.
Explanation / Answer
1) a) True
2) so there will be more flux upwards with time so it will induce a magnetic field downwards
so
currentclockwise so b)
3. generator a)
4) Np/Ns = Vp/Vs = 12000/120 = 100/1 so b)
5) a) True
6) more flux in so induce is out so counter clockwise so b)
7) emf = B l v = 0.8*.15*.2= 0.024 so d)
8) w = 1/sqrt(LC)
b) halve both
9) b) reuce both by half
10) c)
11) c)
12) c) stay the same
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.