The fundamental relationship stating that the voltage (V) across an ohmic conductor equals the current (I) flowing through it multiplied by its resistance (R).
More push (voltage) means more flow (current). More resistance means less flow for the same push.
Showing a random 20 of 50 problems.
Example 1
easy
A 12 V battery is connected to a 4Ω resistor. What current flows?
Example 2
medium
If the voltage across an ohmic resistor increases by 50%, by what percentage does the current change?
Example 3
medium
What voltage is needed to push 0.25 A through a 100Ω resistor?
Example 4
challenge
A resistor's voltage and current are measured: (2 V,1 A) and (6 V,2 A). Is this device ohmic?
Example 5
easy
A 10 V source drives a 5Ω resistor. What current flows?
Example 6
hard
A wire of resistance 5Ω is replaced by a wire of the same material with half the length and double the cross-sectional area. What is the new resistance, and what current will it draw at 10 V?
Example 7
easy
Sketching V on the y-axis vs I on the x-axis for an ohmic resistor gives a straight line through the origin. What is its slope?
Example 8
easy
A current of 0.4 A flows through a 25Ω resistor. What voltage is across it?
Example 9
medium
A 20 V source feeds a 6Ω and 4Ω resistor in parallel. What is the total current from the source?
Example 10
medium
In a series circuit, 2 A flows through a 7Ω resistor. What is the voltage drop across it?
Example 11
easy
A 12 V battery is connected to a 4Ω resistor. What is the current?
Example 12
medium
Two resistors are tested under the same 12 V supply. Resistor A draws 0.6 A; resistor B draws 1.2 A. Which has larger resistance, and by what factor?
Example 13
medium
An ammeter reads 250 mA through a resistor when a voltmeter across it reads 5.0 V. What is the resistance?
Example 14
easy
If voltage across an ohmic resistor doubles, what happens to the current?
Example 15
challenge
An ohmic resistor obeys V=IR with R=50Ω. A time-varying voltage V(t)=10sin(100t) V is applied. Write I(t) and find the peak current.
Example 16
easy
Convert before using Ohm's law: a resistor of 2 kΩ carries 3 mA. What units must you use first?
Example 17
medium
A resistor labelled "5%,100Ω" is connected to a 5 V supply. Give the minimum and maximum currents consistent with the tolerance.
Example 18
easy
A 1.5 V AA cell drives a 30Ω bulb (treat as ohmic). Find the current.
Example 19
easy
Does Ohm's law V=IR apply exactly to a normal filament light bulb at all currents?
Example 20
easy
A 6Ω resistor carries 2 A. What voltage is across it?