CT 29.1aConsider the following four situations. i) An ion (charge +Q) moves to the right.ii) A neutral hydrogen atom (proton, +e, and light electron, -e) moves right.iii) A beam of electrons in a TV shoots rightiv) In an ionic solution, massive positive ions flow right, light negative electrons flow with equal speed to the left.In which of these is the net current ZERO?A: All of the above B: ii only C: iv onlyD: ii and iv only E: None of theseCT 29.1bConsider the following four situations. i) An ion (charge +Q) moves to the right.ii) A neutral hydrogen atom (proton, +e, and light electron, -e) moves right.iii) A beam of electrons in a TV shoots rightiv) In an ionic solution, massive positive ions flow right, light negative electrons flow with equal speed to the left.In which is the net current to the RIGHT?A: i only B: iii only C: iv onlyD: i and iv only E: None of theseCT 29.2aA copper cylinder is machined to have the following shape. The ends are connected to a battery so that a current flows through the copper.Which region has the greatest current density |J|?ABCA, B, C, or D: All three are the sameE:not enough infoCT 29.2bA copper cylinder is machined to have the following shape. The ends are connected to a battery so that a current flows through the copper.Which region has the greatest magnitude of current, i?ABCA, B, C, or D: All three are the sameE: not enough infoCT 29.2cA copper cylinder is machined to have the following shape. The ends are connected to a battery so that a current flows through the copper.Which region has the greatest conductivity ABCA, B, C, or D: All three are the sameE: not enough infoCT 29.2dA copper cylinder is machined to have the following shape. The ends are connected to a battery so that a current flows through the copper.Which region has the greatest magnitude electric field |E|?ABCA, B, C, or D: All three are the sameE: not enough infoCT 29.2eSo far, we have concluded J is greatest in region B. (Using J= E, and J=I/A) The ratio of diameters is A:B:C = 3:1:5.How much larger magnitude is the drift velocity vdin region B compared to C?ABCA: same B: 25x greater C: 5x greater D: slower in region B E: none of theseHint: J = nq vdCT 29.3Two cylindrical resistors are made of the same material (same resistivity ).A) 2 B) 4C) 1/2 D) 1/4E) 11 2Resistor 2 is twice as long and has twice the diameter of resistor.What is the ratio R2/R1?12 VCT 29.7Your (slightly crazed) physics professor wants to grab both poles of a regular 12 V car battery. What happens?A: STOP! Don't let her do it, certain death!B: Warning! (This is going to hurt a little.)C: Let her go for it. (She won't notice a thing...)CT 29.6bHousehold appliances all have V=120 V. What is the approximate resistance of the filament (at operating temperature) of a 100W lightbulb?A) R = 100 OhmsB) R = 144 OhmsC) R = 1250 Ohms D) None of the AboveCT 29.14A household 40W light bulb and a 60W light bulb each has a filament with a certain resistance (when the bulb is on and hot). How do the resistances of the filaments compare?A: R(40W) = R(60W).B: R(40W) > R(60W).C: R(40W) < R(60W).D: Need more info.CT 29.14bThese two bulbs are now put in series. (which is not a normal thing to do) Which bulb glows brighter?A: both have same brightnessB: 40W is brighterC: 60W is brighterD: Not enough infoHints: More power = brighter. When light bulbs are in series, they have the same current. Light bulbs are intended to operate at 120V. V 40 W 60 WCT 29.13eWe start with the left circuit with bulb (A). If we add a second bulb (B) as shown on the right, what happens to bulb A?A) Bulb A is equally bright.B) Bulb A is dimmer than beforeC) Bulb A is brighter than before V A B V ACT 29.9Two identical resistors are wired in series (one behind the other).If there is an electric current I entering the combination, the current exiting the second resistor isA: Equal to B: HalfC: Smaller than, but not necessarily half the current in the first resistor. R R ICT 29.8A: All the current continues to flow through the bulbB: Half the current flows through the bulb, half through the wireC: All the current flows through the wire.Current flows through a light bulb.Suppose a wire is connected across the bulb as shown. When this wire is connected...CT 29.19A 1 resistor is placed in parallel with a 10,000 resistor as shown.The total, equivalent resistance of these two resistors in parallel is...A: a little less than 1 B: a little more than 1 .C: about 5000 D: a little less than 10,000 E: a little more than 10,000 CT 29.12cR1=10 , R2=5 What's the current through the 10 resistor?A: 1 AB: 2 AC: 3AD: 5 AE: 6ACT 29.12dR1=10 , R2=5 What's the voltage drop across the 10 resistor, i.e. V(AB)?A: 30 VB: 20 VC: 15 VD: 10 VE: 0 VCT 29.18What is the voltage at points A, B, C and D?A: VA = VB=6, VC = VD =0 B: VA = VB=12, VC = VD =6 C: VA = VB=12, VC = VD =0D: 12> VB> VA>VC >VD >0groundCT 29.12q'R1=6 , R2=12 Compare the current flowing past points A and BA: IA = IB B: IA= 2 IB C: IA = 0.5 IB D: IA = 3 IB E: IA =(1/3) IBCT 29.10Current is flowing through wires which are part of a circuit, as shown. What is the current in the wire at the bottom right? 2 A I? 1 A A) 1 A to the leftB) 1 A to the rightC) 3 A to the leftD) 3 A to the rightE) none of these/not sureCT 29.27The current directions have been guessed as shown. Which is the correct current equation for this circuit?A) I2=I1+I3 B) I1 = I2+I3 C) I3 = I1+I2 R2R1R3V1 V22I1I3ILoop 1.CT 29.27bWhat is the correct voltage equation for loop 1?A) -V2+I1R1-I2R2=0 B) V2+I1R1-I2R2=0C)-V2-I1R1+I2R2=0 D) V2+I1R1+I2R2=0R2R1R3V1 V22I1I3ILoop 1.CT 29.23Compare the brightness of A with the combined brightness of B and C together.(Assuming identical bulbs)A: P(A)=P(B+C)B: P(A) > P(B+C)C: P(A) < P(B+C)(where P means “total power of”)V=12VAB CCT 29.35The circuit shown contains an ideal battery with 2 identical bulbs. When the switch is closed, what happens to the currents through points A and B?A) IAsame, IBB) IA, IBsameC) IAsame, IBsame D) IA, IBE) IA, IBV IBBAIACT 29.22bWhich bulb is the brightest? (All bulbs are identical)CT 29.37A: A glows, B changesB: A glows, B stays sameWhat happens to the (identical) bulbs when the switch is closed? switch 12 V B A 12 V C: A stays same, B
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