IV graphs Flashcards

1
Q

What components do I need to measure the resistance of a resistor?

A
  • Ammeter
  • Voltmeter
  • Variable resistor
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2
Q

Why is a variable resistor needed?

A
  • Changes current of circuit
  • Changes P.D across component
  • GET A RANGE OF VALUES
    OR…. other way
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3
Q

What are the 2 ways in this experiment that I can increase the voltage?

A
  • By powerpack
  • By variable resistor
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4
Q

How do you collect negative results for P.D and current?

A
  • Switch terminals of battery around.
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5
Q

What does the straight line graph of a resistor tell you about its resistance?

A
  • Shows resistance is constant.
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6
Q

What is the relationship between P.D and Current in graph of resistor?

A
  • Directly proportional relationship
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7
Q

What is an “ohmic conductor?”

A
  • One that obeys Ohms Law
  • P.D and current are directly proportional and temp is constant.
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8
Q

Q.)

Describe how to use variable resistor to vary the current in the circuit.

A
  • Adjust the variable resistor to increase resistance through it.
  • Increasing resistance through it decreases current of overall circuit.
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9
Q

What happens to the brightness of the filament bulb when we increase P.D?

A
  • Brightness increases
  • More energy transferred
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10
Q

What happens to the resistance of a filament lamp as brightness increases?

A
  • Resistance increases as brightness does.
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11
Q

What happens to the resistance of the lamp as you increase the P.D across it ?

A
  • The resistance increases as you increase P.D.
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12
Q

Why does an increase in temperature increase resistance?

A
  • Metal ions vibrate more
  • Flow of electrons is more difficult.
  • The resistance increases.
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13
Q

What causes the increase in temperature in a filament bulb?

A

The increase in current.

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14
Q

How is the steepness of a line related to resistance on an IV graph?

A
  • Steeper line: lower resistance
  • Shallow line: high resistance
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15
Q

Why does a shallow line have a high resistance?

A
  • Low current for the same PD
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16
Q

If the axis on IV graph changes to V on y and I on x… what happens to resistance?

A

Shallow line = low resistance
Steeper line = high resistance

low P.D. = low resistance
High P.D = high resistance

17
Q

What is the variable resistor changing when you experiment I + V in diodes?

A
  • Current through diode
  • see effect on P.D
18
Q

What are the steps to completing the IV experiment for diode?

A

1.) Set up electrical circuit as shown
2.) Adjust variable resistor (take new values for current + PD.)
3.) Repeat to collect 5 readings
4.) Switch terminals aroud to plot negative values
5.) Negative direction = Zero!!

19
Q

What type of resistance does diode have in poisitive direction?

A
  • Low resistance
20
Q

What is a thresh hold voltage?

A
  • This is the voltage needed for current to flow through.
21
Q

Why is a thresh hold voltage useful?

A
  • Prevents current “accidently” flowing in opposite direction.
22
Q

Q.)

Use the Diode IV graph to explain why current passes through diode.

(3 points)

A
  • It has reached thresh hold voltage
  • Current flowing in correct direction
  • Low resistance when voltage is positive.
23
Q

Give a descritpion of a filament lamp.

A
  • Has a thin wire that heats up and emitts light.
  • Non- ohmic conductor
24
Q

Q.)

How can you tell that an IV graph is a diodes’ in terms of resistance?

A
  • High resistance in one direction
  • Low resistance in other direction
25
Q

Which type of graph obeys Ohms Law and has a constant resistance, linear or non- linear?

A
  • Linear graphs
26
Q

What are non- linear graphs?

A
  • Ones that donnot obey Ohms Law and have varying resistances due to changes in temperature.
27
Q

Give examples of non- linear elements.

A
  • Filament bulb
  • Diode
  • Thermistor
  • LDR
28
Q

Give examples of linear elements.

A
  • Wire
  • Resistor
29
Q

What is meant by the term “negative potential difference?”

A
  • Potential difference values are in opposite direction ie. negative…
30
Q

Why do we add an extra resistor when we investigate IV graphs for diodes?

A
  • Lowers the current
  • BECAUSE the current is low we need a miliammeter.