The voltage drop across a resistor in a simple circuit equals the voltage output of the battery.
Making connections: conservation of energy
In a simple electrical circuit, the sole resistor converts energy supplied by the source into another form. Conservation of energy is evidenced here by the fact that all of the energy supplied by the source is converted to another form by the resistor alone. We will find that conservation of energy has other important applications in circuits and is a powerful tool in circuit analysis.
Phet explorations: ohm's law
See how the equation form of Ohm's law relates to a simple circuit. Adjust the voltage and resistance, and see the current change according to Ohm's law. The sizes of the symbols in the equation change to match the circuit diagram.
What is the resistance of a bulb if the current in it is 1.25 A when a 4 V voltage supply is connected to it? If the voltage supply is increased to 7 V, what will be the current in the bulb?
A simple circuit
is one in which there is a single voltage source and a single resistance.
One statement of Ohm's law gives the relationship between current
,
voltage
,
and resistance
in a simple circuit to be
Resistance has units of ohms (
), related to volts and amperes by
.
There is a voltage or
drop across a resistor, caused by the current flowing through it, given by
.
Conceptual questions
The
drop across a resistor means that there is a change in potential or voltage across the resistor. Is there any change in current as it passes through a resistor? Explain.
(a) Find the voltage drop in an extension cord having a
resistance and through which 5.00 A is flowing. (b) A cheaper cord utilizes thinner wire and has a resistance of
. What is the voltage drop in it when 5.00 A flows? (c) Why is the voltage to whatever appliance is being used reduced by this amount? What is the effect on the appliance?
(a) 0.300 V
(b) 1.50 V
(c) The voltage supplied to whatever appliance is being used is reduced because the total voltage drop from the wall to the final output of the appliance is fixed. Thus, if the voltage drop across the extension cord is large, the voltage drop across the appliance is significantly decreased, so the power output by the appliance can be significantly decreased, reducing the ability of the appliance to work properly.
A power transmission line is hung from metal towers with glass insulators having a resistance of
What current flows through the insulator if the voltage is 200 kV? (Some high-voltage lines are DC.)
I am a university student of Myanmar.I am first year,first semester.I want to learn about physics.
Maung
two charges qA and qB are separated by a distance x. if we double the distance between the charges and triple the magnitude of the charge A, what happens to the magnitude of the force that charge A exerts on charge B.
what happens to the magnitude of the force that charge B exerts on charge A
a reflected ray on a mirror makes an angle of 20degree with the incident ray when the mirror is rotated 15degree what angle will the incident ray now make with the reflected ray
Roofs are sometimes pushed off vertically during a tropical cyclone, and buildings sometimes explode outward when hit by a tornado. Use Bernoulli’s principle to explain these phenomena.
Insulators (nonmetals) have a higher BE than metals, and it is more difficult for photons to eject electrons from insulators. Discuss how this relates to the free charges in metals that make them good conductors.
