Practice: A resistor has a current through it of 5 A. If the EMF across the resistor is 10 V, what is the resistance of this resistor?

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Practice: A resistor has a current through it of 5 A. If the EMF across the resistor is 10 V, what is the resistance of this resistor?

Practice: Two resistors are made of the same material, one twice as long as the other. If the current through the shorter resistor is 5 A, what is the current through the longer resistor if they both have the same potential difference?

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If a cylindrical metal wire is stretched to 4 times of its original length, what is the resulting resistance R, compared with the original resistance R0?
A) R = 16R0
B) R = R0/16
C) R = R0/4
D) R = 4R0

You are given a copper bar of dimensions 3 cm x 5 cm x 8 cm and asked to attach leads to it in order to make a resistor. If you want to achieve the SMALLEST possible resistance, you should attach the leads to the opposite faces that measure
(a) 3 cm x 8 cm.
(b) 5 cm x 8 cm.
(c) 3 cm x 5 cm.
(d) Any pair of faces produces the same resistance.

Two pieces of metal are shaped into resistors and are connected end-to-end. The first resistor, R1, has twice the length of the second resistor, R 2, but an equal diameter. If the resistors are made of the same material, and are connected to a voltage source, what is the ratio of the voltage across each resistor, V1 / V2 ?

The headlight of a car has a resistance R = 3.4Ω. The headlight consists of a tungsten wire (resistivity p = 5.6 x 10-8 Ω • m) of length 12.4 cm. What is the cross-sectional area of the wire?

The current in a resistor decreases by 2.27 A when the voltage applied across the resistor decreases from 12.3 V to 4.26 V. Find the resistance of the resistor.
1. 0.892638
2. 4.37778
3. 7.76768
4. 3.54185
5. 2.65823
6. 4.25074
7. 4.50218
8. 3.12424
9. 3.48214
10. 5.13265

What is the resistance of a Nichrome wire at 0.0°C if its resistance is 100.00 Ω at 45°C? The temperature coefficient for nichrome is 4.00x10-4 (°C)-1A. 100.5 ΩB. 100.0 ΩC. 98.23 ΩD. 96.46 ΩE. 94.23 Ω.

A long, uniform conducting wire with resistance R is connected to the terminals of a battery with emf V, dissipating a power P. If the cross-sectional area of the wire is halved, what is the new total power dissipated?A. 2PB. ¼ PC. 4PD. ½ PE. P

Consider two conductors 1 and 2 made of the same ohmic material (ρ 1 = ρ2). Denote the length of the conductor by ℓ and the radius by r. The same voltage V is applied across the ends of both conductors. If r2 = 2 r1 , and ℓ2 = 2 ℓ1 , find the ratio I 2 / I1 of the currents.
1. I2 / I1 = 8
2. I2 / I1 = 1/2
3. I2 / I1 = 1
4. I2 / I1 = 1/4
5. I2 / I1 = 1/8
6. I2 / I1 = 2
7. I2 / I1 = 4

The length of a certain wire is doubled and at the same time its radius is increased by a factor of 4. What is the change in the resistance of this wire?A) It is reduced by a factor of 8.B) It increases by a factor of 4.C) It increases by a factor of 8.D) It is reduced by a factor of 4.

The resistivity of a 1.0 m long wire is 1.72 x 10 -8 Ωm and its cross-sectional area is 2.0 x 10-6 m2. If the wire carries a current of 0.2 A, what is the voltage across the wire?

Pure silicon contains approximately 1.0 x 1016 free electrons per cubic meter.Resistivities at Room Temperature (20 °C)(a) Referring to the table above, calculate the mean free time for silicon at room temperature.(b) Your answer in part (a) is much greater than the mean free time for copper. Why, then, does pure silicon have such a high resistivity compared to copper?

Resistor color codes:a) What is the resistance of a resistor with the band colors Green Blue Brown? b) What is the resistance of a resistor with the band colors Red Green Black? c) What colors would you see on a 75 kΩ resistor? d) What colors would you see on a 580 Ω resistor?

a) Explain the distinction between an ohmic and non-ohmic material, in terms of how the current and resistance behave as the voltage difference across the material is changed.b) Now, imagine a single-loop circuit with a battery, two wires, and a 10 Ohm resistor. The wires are also ohmic, but with a resistance much smaller than the 10 Ohm resistor. Despite the disparity in resistance, the current in the wire is the same as that through the resistor since they are in series. Using Ohm's Law, explain how this uniformity in current relates to (or arises from) the individual potential differences across the wire and resistor.

Which of the following statements are true? More than one answer may be correct - select all correct answers.Select one or more:a. A material that obeys Ohm's law reasonably well is called an ohmic conductor or a linear conductor.b. The resistance of a conductor is proportional to the conductivity of the material of which the conductor is composed.c. Semiconductors have resistivity values that are larger than those of insulators.d. The resistance of a conductor is proportional to the resistivity of the material of which the conductor is composed.e. Good conductors of electricity have larger conductivity values than insulators.

Imagine a single-loop circuit with a battery, and three resistors R1, R2, R3 connected in series. Resistance is ignorable except for the resistors. Resistors are ohmic. Answer the following questions a. Which (if any) physical quantity- among resistance R, current I, and voltage V must be the same for the three resistors? b. How are R, I, and V related for each resistor in this circuit? Answer with an equation involving these three quantities.

Consider the circuit shown. (Intro 1 figure) All wires are considered ideal; that is, they have zero resistance. We will assume for now that all other elements of the circuit are ideal, too: The value of resistance is a constant, the internal resistances of the battery and the ammeter are zero, and the internal resistance of the voltmeter is infinitely large.Intro 1:Intro 2:Part A What is the reading V of the voltmeter?Express your answer in terms of the EMF ℰ. Part BThe voltmeter, as can be seen in the figure, is connected to points 1 and 3. What are the respective voltage differences between points 1 and 2 and between points 2 and 3?a) 0; ℰb) 0; -ℰc) ℰ; 0d) ℰ;ℰPart CWhat is the reading I of the ammeter?Express your answer in terms of ℰ and R.Now assume that the battery has a nonzero internal resistance r (but the voltmeter and the ammeter remain ideal). (Intro 2 figure)Part DWhat is the reading of the ammeter now?Express your answer in terms of ℰ, r, and R.Part EWhat is the reading of the voltmeter now?Express your answer in terms of ℰ, r, and R.

R=ρL/A where L is the length and A is the cross-sectional area of the wire. From the wire in question 4, the length of the wire is 10m, the cross-sectional area of the wire is 3.25×10-3 cm2. The relative uncertainty of L and A are both 10%. What are the resistivity of the wire and its uncertainty? The value of R is 1.345 ohms

What is the purpose of the rheostat in the resistance and resistivity experiment?1) to limit the current in the circuit.2) to overheat.3) as an aid to adjusting the current in the circuit.4) it is the resistor whose resistance is to going to be determined.

Two identical lightbulbs are connected in series to a single 9.0 V battery.a. Sketch the circuit.b. Sketch a graph showing the potential as a function of distance through the circuit, starting with V = 0V at the negative terminal of the battery.

A. Consider a circuit containing five identical light bulbs and an ideal battery. Assume that the resistance of each light bulb remains constant. Rank the bulbs (A through E) based on their brightness.Rank from brightest to dimmest. To rank items as equivalent, overlap them.B. The switch shown is initially closed. What happens when it is opened?What happens to bulb C?a) It gets dimmer.b) It gets brighter.c) There is no change.

A 0.0075 v/m electric field creates a 3.9 mA current in a 1.0 mm diameter wire. What material is the wire made of?

Electrons moving through the circuit in the attached figure will go through the resistorA. go from a to b.B. go from b to a.

You have a circuit consisting of four 4.5 V D-cell batteries in series, some wires, and a light bulb. The bulb is lit and the current flowing through the bulb is 0.50 A. You may assume that all of the voltage drop occurs in the light bulb. What is the resistance of the bulb?

During open-heart surgery, a defibrillator can be used to bring a patient out of cardiac arrest. The resistance of the path is 500 Ω and a 10.0-mA current is needed. What voltage should be applied?

What happens to the resistance of most common metals as the temperature of the metal increases?Select one:a. The resistance increases as temperature increases.b. Whether resistance increases or decreases as temperature increases depends on the type of metal.c. The resistance decreases as temperature increases.d. The resistance remains constant as temperature increases.

Which of the following materials is the poorest electrical conductor?A. NichromeB. CopperC. Aluminum D. Brass

In the figure R1 = 2.75R, the ammeter resistance is zero, and the battery is ideal. What multiple of ε/R gives the current in the ammeter?

For this diagram, include three extra circuit symbols:A. An ammeter measuring the current at point AB. A voltmeter measuring the voltage drop across the topmost resistor (the one in parallel with the topmost bulb)C. An ammeter measuring the current through the rightmost resistor

An ammeter is connected in series to a battery of voltage Vb and a resistor of unknown resistance Ru (Figure 1) . The ammeter reads a current Io. Next, a resistor of unknown resistance Rr is connected in series to the ammeter, and the ammeter's reading drops to I1. Finally, a second resistor, also of resistance Rr, is connected in series as well. Now the ammeter reads I2.If I1/I0=4/5, find I2/I0.Express the ratio I2/I0 numerically.I2/I0 =

If the voltage across a circuit of constant resistance is doubled, how is the current in the circuit affected?Select one:a. The current is doubled.b. The current is reduced by a factor of 2.c. The current is quadrupled.d. The current is reduced by a factor of 4.e. The current remains constant.

If the resistance in a circuit connected to a constant current is halved, how is the voltage in the circuit affected?Select one:a. The voltage is reduced by a factor of 4.b. The voltage is quadrupled.c. The voltage remains constant.d. The voltage is reduced by a factor of 2.e. The voltage is doubled.

The figure is a current-versus-potential-difference graph for a cylinder.What is the cylinder's resistance?

Suppose that ℰ = 65 V. (Figure 1)What is the potential difference across the 40 Ω resistor? Express your answer with the appropriate units.What is the potential difference across the 60 Ω resistor?

Determine the magnitude of the current in the (a) 8.0- and (b) 2.0-? resistors in the drawing.

According to Table 1, which of the following materials is the best electrical conductor? Brass Copper Aluminum Nichrome

A copper wire is stretched so that its length increases and its diameter decreases. As a result, A. The wire's resistance decreases, but its resistivity stays the same. B. The wire's resistivity decreases, but its resistance stays the same. C. The wire's resistance increases, but its resistivity stays the same. D. The wire's resistivity increases, but its resistance stays the same.

Rank in order, from largest to smallest, the resistivities ρ1 to ρ5 of these wires. Rank from largest to smallest. To rank items as equivalent, overlap them.The wires in (Figure 1) all have the same resistance; the length and radius of each wire are noted.

Consider two wires, one aluminum with resistivity 2.65 × 10–8 Ω•m and one copper with 1.72 × 10–8 Ω•m. Find the ratio of the diameter of aluminum to copper wire, if they have the same resistance per unit length (as they might in household wiring).

The figure is a current-versus-potential-difference graph for a cylinder. What is the cylinder's resistance?

Which of the following will increase the resistance of a wire?Check all that apply.a) Decreasing the resistivity of the material the wire is composed of will increase the resistance of the wire.b) Increasing the length of the wire will increase the resistance of the wire.c) Decreasing the length of the wire will increase the resistance of the wire.d) Decreasing the cross-sectional area of the wire will increase the resistance of the wire.e) Increasing the cross-sectional area of the wire will increase the resistance of the wire.f) Increasing the resistivity of the material the wire is composed of will increase the resistance of the wire.

The diameter of a specific copper wire is 8.325 mm, and has a resistivity of 1.72 x 10-8Ω-m. Find the resistance of a 0.85 km length of such wire used for power transmission in Ω.

A wire of length L and cross-sectional area A has resistance R.What will be the resistance Rstretched of the wire if it is stretched to twice its original length? Assume that the density and resistivity of the material do not change when the wire is stretched.

In household wiring, copper wire 2.05 mm in diameter (12 gauge) is often used. Find the resistance of a 24.0 m length of this wire. Note the resistivity of copper is 1.72*10-8 Wm.

Which of the following will increase the resistance of a wire? (More than one answer may be correct - select all correct answers).Select one or more:a. Increasing the cross-sectional area of the wire will increase the resistance of the wire.b. Increasing the resistivity of the material the wire is composed of will increase the resistance of the wire.c. Increasing the length of the wire will increase the resistance of the wire.d. Decreasing the resistivity of the material the wire is composed of will increase the resistance of the wire.e. Decreasing the cross-sectional area of the wire will increase the resistance of the wire.f. Decreasing the length of the wire will increase the resistance of the wire.

Consider two copper wires with the same cross-sectional area. Wire A is twice as long as wire B. How do the resistivities and resistances of the two wires compare?Select one:a. The wires have the same resistivity, but wire A has half the resistance of wire B.b. Wire A has twice the resistivity of wire B, but the wires have the same resistance.c. Wire A has half the resistivity and half the resistance of wire B.d. Wire A has twice the resistivity of wire B, and wire A has twice the resistance of wire Be. The wires have the same resistivity, but wire A has twice the resistance of wire B.

The wires in (Figure 1) all have the same resistance; the length and radius of each wire are noted. Rank in order, from largest to smallest, the resistivities ρ1 to ρ5 of these wires.

In household wiring, copper wire 2.05 mm in diameter (12 gauge) is often used. Find the resistance of a 24.0 m length of this wire. Note the resistivity of copper is 1.72×10-8 Ω·m.

Pencil "lead" is actually carbon. What is the resistance of the 0.760 mm-diameter, 7.00cm-long lead from a mechanical pencil?

A circuit calls for a 0.900mm -diameter copper wire to be stretched between two points. You don't have any copper wire, but you do have aluminum wire in a wide variety of diameters. What diameter (in mm) aluminum wire will provide the same resistance?

What is the equivalent resistance between points a and b in the figure?

What is the equivalent resistance between points a and b in the figure (Figure 1)? Express your answer using one significant figure.

A wire with resistance R is connected to the terminals of a 6.0 V battery. What is the potential difference ΔV between the ends of the wire and the current I through it if the wire has the following resistances?a. 1.0 Ωb. 2.0 Ωc. 3.0 Ω

The motor in a toy car operates on 6.00 V, developing a 4.50 V back emf at normal speed. If it draws 3.00 A at normal speed, what current does it draw when starting?

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