Physics 5.1.3-4 Resistivity and Circuits

26 flashcards · Physics · by TheoTyson

1. What is resistivity?

   A measure of how easily a material conducts electricity.

2. How does length affect the resistance?

   The longer the wire, the higher the resistance.

3. How does the area affect the resistance?

   The greater the area, the lower the resistance.

4. How does resistively affect the resistance?

   The higher the resistivity, the higher the resistance.

5. What is a thermistor?

   A resistor with a resistance that depends on its temperature.

6. How does the resistance of a NTC thermistor change as temperature changes?

   As temperature increases, the resistance of the thermistor decreases.

7. What is the current-voltage\text{current-voltage}current-voltage graph for an NTC thermistor?

8. What is the resistance-temperature\text{resistance-temperature}resistance-temperature graph for an NTC thermistor?

9. What is the circuit symbol for a thermistor?

10. What can a thermistor be used as?

    Temperature sensor.

11. What is the resistivity of a superconductor when the temperature is below the critical temperature?

    Zero resistivity.

12. What is the critical temperature of a superconductor?

    The temperature below which the superconductor has zero resistivity.

13. How do superconductors work?

    If the resistivity is zero, then there is no resistance, and none of the energy is wasted.

14. How can superconductors be used with strong electromagnets?

    The magnetic field would not need a constant power source, as long as it was below the critical temperature.

15. How can superconductors be used in power cables?

    If the cables have zero resistance, then no energy will be lost along the transmission of long power cables.

16. What is power?

    The rate of transfer of energy.

17. How do you find the resistance of resistors in series?

    R total=R 1+R 2+R 3\text{R}_{\text{ total}} = \text{R}_{\text{ 1}} + \text{R}_{\text{ 2}} + \text{R}_{\text{ 3}}R total​=R 1​+R 2​+R 3​

18. How do you find the resistance of resistors in parallel?

    1R total=1R 1+1R 2+1R 3\frac{1}{\text{R}_{\text{ total}}} = \frac{1}{\text{R}_{\text{ 1}}} + \frac{1}{\text{R}_{\text{ 2}}} + \frac{1}{\text{R}_{\text{ 3}}}R total​1​=R 1​1​+R 2​1​+R 3​1​

19. What is Kirchhoff's first law?

    The total current entering a junction is equal to the total current leaving it.

20. What is Kirchhoff's second law?

    The same of the all of the voltages in a circuit is equal to the battery voltage.

21. How does current vary in a series circuit?

    The current is the same everywhere in a series circuit.

22. How does voltage vary in a series circuit?

    The voltage is split across the series circuit, but the sum of the voltages is equal to the voltage of the battery.

23. How does current vary in a parallel circuit?

    The current is split across the parallel circuit, but the sum of the currents is equal to the total current.

24. How does voltage vary in a parallel circuit?

    The voltage across each branch is the same.

25. How do you find the voltage of cells in series?

    Vtotal=V1+V2+V3\text{V}_{\text{total}} = \text{V}_{\text{1}} + \text{V}_{\text{2}} + \text{V}_{\text{3}}Vtotal​=V1​+V2​+V3​

26. How do you find the voltage of cells in parallel?

    Vtotal=V1=V2=V3\text{V}_{\text{total}} = \text{V}_{\text{1}} = \text{V}_{\text{2}} = \text{V}_{\text{3}}Vtotal​=V1​=V2​=V3​