Capacitors circuits

Two resistors have the same resistivity and cross-sectional area. One is twice as long as the other. What is the voltage on the longer resistor? 

• 12 V
• 8 V
• 6 V
• 4 V

Tags

NGSS.HS-PS3-5

A parallel plate capacitor is connected to a cell of constant emf. The plates are moved further apart without disconnecting the cell. What happens to the capacitance and voltage across the plates?

• capacitance increases; voltage remains constant
• capacitance remains constant; voltage decreases
• capacitance decreases; voltage increases
• capcitance decreases; voltage remains constant

Which graph shows how the current through an ideal ohmic resistor changes with voltage?

• A
• B
• C
• none of the above

Capacitors C₁ and C₂ are connected in parallel and a potential difference is applied to the combination. If the capacitor that is equivalent to the combination has the same potential difference, then the charge on the equivalent capacitor is the same as: 

• the charge on C₁
• the sum of the charges on C₁ and C₂
• the difference of the charges on C₁ and C₂
• the product of the charges on C₁ and C₂

Two identical capacitors are connected in series and two, each identical to the first, are connected in parallel. The equivalent capacitance of the series connection is ________ the equivalent capacitance of parallel connection. 

• twice
• four times 
• half 
• one fourth

Capacitors C₁ and C₂ are connected in series. The equivalent capacitance is given by: 

• C₁C₂/(C₁ + C₂) 
• (C₁ + C₂)/C₁C₂
• 1/(C₁ + C₂) 
• C₁ + C₂

Capacitor C₁ and C₂ are connected in parallel. The equivalent capacitance is given by: 

• C₁ + C₂
• 1/(C₁ + C₂) 
• C₁C₂/(C₁ + C₂) 
• (C₁ + C₂)/C₁C₂

Each of the four capacitors shown is 500 microF. The voltmeter reads 1000V. The magnitude of the charge on each capacitor plate is:

• 0.2 C

• 0.5 C

• 20 C

• 50 C

A parallel-plate capacitor has a plate area of 0.2 m² and a plate separation of 0.1 mm. To obtain an electric field of 2.0 ´ 10⁶ V/m between the plates, the magnitude of the charge on each plate should be:

• 3.5 ´ 10^-6 C
• 7.1 ´ 10^-6 C 
• 1.4 ´ 10^-5 C
• 1.8 ´ 10^-5 C

If both the plate area and the plate separation of a parallel-plate capacitor are doubled, the capacitance is: 

• doubled
• halved
• unchanged 
• one-fourth the original