Current, Potential Difference and Resistance (3) Flashcards

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1
Q

Which lamp will be brighter at any potential difference?

A

A is brigher because it has a higher current than lamp B at any p.d. Therefore, A has a higher power output than bulb B

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2
Q

Lamp B has the higher potential resistance at any potential difference. Explain how the figure above shows this

A

Lower current than Lamp A for the same potential difference and lower gradient than Lamp A

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3
Q

Both lamps behave like ohmic conductors through a range of values of potential difference.
Use the figure above to determine the range for these lamps.
Explain your answer

A

0-2 volts as for an ohmic conductor current is directly proportional to potential difference so resistance is constant

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4
Q

Which one of the following is most likely to include a thermistor?

A

3rd box (an automatic circuit to switch a heating system on and off)

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5
Q

Why is it important that ammeters have a very low resistance?

A

So the ammeter reduced current as little as possible

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6
Q

Scientists in different countries use the same temperature scale to measure temperature.
Suggest one advantage of doing this

A

Easier to share results

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7
Q

One of the changes the student makes is to replace the thermistor with an LDR.
Describe what other changes the student should make to the apparatus

A

Replace Bunsen burner and water with a lamp and replace thermometer with light sensor

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8
Q

It would not be safe to connect the electric cooker hob to the mains electricity supply by plugging it into a power socket.
Why?

A

Maximum current exceeds maximum safe current for a 2.5 mm squared wire

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9
Q

An 18 V battery could not be used as the input of a transformer.
Explain why

A

Needs alternating current. Battery is direct current.

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