Class 12 Current
Physics Current Electricity Level: High School
Lightbulb A is rated at 120 V and 40 W for household applications . Lightbulb B is rated at 12 v and 40 W for automotive applications .a) What is the current through each bulb ?
b) What is the resistance of each bulb ?
c) In one hour, how much charge passes through each bulb ?
d) In one hour, how much energy does each bulb use ?
e) Which bulb requires larger diameter wires to connect its power source and the bulb ?
Physics Current Electricity Level: High School
Two identical light bulbs are placed any-where in any circuit . Let the current through #1 be i1 and the power consumed by #1 be P1, and the corresponding quantities i2 and P2 for bulb #2 . If the ratio P1/P2 = 2 , the ratio i1/i2 will be given by ?(i) i1/i2 = 1/6
(ii) i1/i2 = 2
(iii) Not enough information
(iv) i1/i2 = square root 2 .
Physics Current Electricity Level: High School
Find the ratio V’1/V’2 of the voltage drop .(i) V’1/V’2 = 5/3
(ii) V’1/V’2 = 2
(iii) V’1/V’2 = 2/3
(iv) V’1/V’2 = 1/7
Physics Current Electricity Level: High School
Consider a circuit with three identical bulbs , an ideal battery , and a switch S . Assume the resistance of each light bulb remains constant . Leaving S open,(a) compare i0, i1 and i2 .
(i) i0 < i2 < i1
(ii) i1 > i0 = i2
(iii) i0 = i1 = i2
(b) Now we close S . Denote the open switch circuit quantities as unprimed , and the closed switch circuit quantities as primed . Determine i’1/i1.
(i) i’1/i1 = 2
(ii) i’1/i1 = 5/3
(iii)i’1/i1 = 4/3
(iv)i’1/i1 = 1/3
(c) Determine i’2/i2
(i) i’2/i2 = 1/ 2
(ii) i’2/i2 = 1
(iii) i’2/i2 = 5/3
(iv) i’2/i2 = 1/6
Physics Current Electricity Level: High School
When switch S is open , the ammeter in the circuit shown reads 2.0 A . when S is closed , the ammeter reading :a) Increases slightly .
b) Remains the same .
c) Decreases slightly .
d) Double .
e) Halves .
Physics Current Electricity Level: High School
A total resistance of 3.0 Ohm is to be produced by combining an unknown resistor R with a 12 Ohm resistor . What is the value of R and how is to be connected to the 12 Ohm resistor ?a) 4.0 Ohm, parallel
b) 4.0 Ohm, series
c) 2.4 Ohm, parallel
d) 2.4 Ohm, series
e) 9.0 Ohm, series
Physics Current Electricity Level: High School
Kirchoff's Law
Four wires meet at a junction . The first carries 4 A into the junction, the second carries 5 A out of the junction , and the third carries 2 A out of the junction , the fourth carries ?a) 7 A out of the junction
b) 7 A into the junction
c) 3 A out of the junction.
d) 3 A into the junction.
e) 1 A into the junction.
Physics Current Electricity Level: High School
The emf of a battery is equal to its terminal potential difference of ?a) Under all conditions
b) Only when the battery is being charged .
c) Only when a large current is in the battery .
d) Only when there is no current in the battery .
e) Under no conditions .
Physics Current Electricity Level: High School
Kirchoff's Law
“ The sum of the emf’s and potential differences around a closed loop equals zero” is a consequence of ?a) Newton’s third law.
b) Ohm’s law.
c) Newton’s second law.
d) Conservation of energy.
e) Conservation of charges.
Physics Current Electricity Level: High School
At 20 degrees celcius , the carbon resistor in an electric circuit connected to a 50.0 V battery has a resistance of 200 ohms . what is the current in the circuit when the temperature of the carbon rises to 80 degrees celcius ?