Quiz: the voltage divider

Question 1R1 = 2 kΩ, R2 = 1 kΩ across 9 V. V_out (across R2) is:

1. 1 V
2. 3 V
3. 4.5 V
4. 6 V

Question 210 V across 10 k (top) + 40 k (bottom). What is V_out?

Question 3Both resistors of a divider are made 10 times bigger. V_out (no load):

1. is 10× bigger
2. is 10× smaller
3. stays the same
4. becomes zero

Question 4An LDR is at the bottom of a divider. It gets dark. V_out:

1. rises
2. falls
3. stays the same
4. reverses

Question 5What is the output resistance (R_th) of a 30 k / 60 k divider?

Question 6A 12 V, 10 k / 10 k divider gets a 10 kΩ load. V_out becomes:

Question 7Why is a divider a bad way to run a 5 V motor from 12 V?

1. Resistors cannot carry DC
2. The motor's current collapses V_out and wastes power in R1
3. Dividers only work with AC
4. The motor would run backwards

Question 8A 22 k / 10 k divider on a battery gives 3.5 V at the ADC. The battery is at:

Question 9Which pair is the usual way to bring a 5 V signal down to a 3.3 V input?

1. 2 kΩ top, 1 kΩ bottom
2. 1 kΩ top, 2 kΩ bottom
3. 1 kΩ top, 1 kΩ bottom
4. 10 Ω top, 20 Ω bottom