Multiple Choice
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?
27. Resistors & DC Circuits
Resistors and Ohm's Law
Back27. Resistors & DC Circuits
Resistors and Ohm's Law
- Multiple Choice
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 and cross-sectional area?
- Multiple ChoiceA wire runs from the positive plate of a capacitor, into lightbulb 1, then out from lightbulb 1 directly into lightbulb 2. When lightbulb 2 is connected to the negative plate of the capacitor, what is true about the charge moving through the two lightbulbs?
- Multiple ChoiceA copper wire with a radius of and a length of is connected across the terminals of a battery. How much current flows in the wire?
- Multiple ChoiceA certain wire has length L and radius r, and a resistance of R. That wire is melted down and the same volume of the same metal is used to produce a wire with length 2L. What is the resistance of the resulting wire?
- Multiple ChoiceA copper wire and an aluminum wire have the same diameter. If the copper wire is long, how long is the aluminum wire if they have the same resistance?
- Multiple ChoiceWhich of the following is true about the change in potential across a resistor in a circuit?
- Open QuestionA copper transmission cable 100 km long and 10.0 cm in diameter carries a current of 125 A. (b) How much electrical energy is dissipated as thermal energy every hour?
- Open Question(b) What is the resistance of a carbon rod at 25.8°C if its resistance is 0.0160 Ω at 0.0°C?
- Open QuestionA hollow aluminum cylinder is 2.50 m long and has an inner radius of 2.75 cm and an outer radius of 4.60 cm. Treat each surface (inner, outer, and the two end faces) as an equipotential surface. At room temperature, what will an ohmmeter read if it is connected between (a) the opposite faces and (b) the inner and outer surfaces?
- Open QuestionIn household wiring, copper wire 2.05 mm in diameter is often used. Find the resistance of a 24.0-m length of this wire.
- Open QuestionA ductile metal wire has resistance R. What will be the resistance of this wire in terms of R if it is stretched to three times its original length, assuming that the density and resistivity of the material do not change when the wire is stretched? (Hint: The amount of metal does not change, so stretching out the wire will affect its cross-sectional area.)
- Open QuestionA cylindrical tungsten filament 15.0 cm long with a diameter of 1.00 mm is to be used in a machine for which the temperature will range from room temperature (20°C) up to 120°C. It will carry a current of 12.5 A at all temperatures. (c) What will be the maximum potential drop over the full length of the filament?
- Open QuestionA 2.0-mm-diameter wire formed from a composite material has a resistivity that decreases with distance along the wire as ρ=ρ₀e^−αˣ, where ρ₀=4.0×10^−5 Ω m , x (in m) is measured from one end of the wire, and the constant α=4.0 m^−1. What is the resistance of a 50-cm-long length of this wire?
- Open QuestionA hollow copper sphere has inner radius 1.0 cm and outer radius 2.5 cm. A 5.0 A current flows radially outward from the inner surface to the outer surface. What is the electric field strength at r=2.0 cm?