2.1 Current, potential difference and resistance

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Question 20

An industrial lab technician is testing the combined resistance of identical heating elements connected in series for a high-temperature kiln. The technician uses a digital multimeter to measure the total resistance of the elements. Table 1 displays the results when 6 identical heating elements are connected in series.

Table 1

Number of elements	Reading 1 ( $Ω\Omega$ )	Reading 2 ( $Ω\Omega$ )	Reading 3 ( $Ω\Omega$ )	Mean ( $Ω\Omega$ )
6	143.9	144.0	144.1	144.0

Calculate the mean resistance of a single heating element.

[2]

What was the resolution of the digital multimeter used by the technician?

$Ω0.1\ \Omega$
$Ω0.5\ \Omega$
$Ω1.0\ \Omega$
$Ω144.0\ \Omega$

[1]

How do the results show that the technician's measurements were precise?

The measurements are close to the true value.
The measurements are grouped closely together.
The measurements are reproducible by other technicians.

[1]

How would a graph of mean total resistance against the number of elements show that the total resistance is directly proportional to the number of elements?

The plot gives a straight line that would pass through the origin.
The plot gives a curve that levels off at high numbers.
The plot gives a linear relationship with a positive y-intercept.

[1]

Predict the mean total resistance of 15 of these heating elements connected in series.

[2]

2.1 Current, potential difference and resistance

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Question 20

Table 1

Number of elements	Reading 1 ( $Ω\Omega$ )	Reading 2 ( $Ω\Omega$ )	Reading 3 ( $Ω\Omega$ )	Mean ( $Ω\Omega$ )
6	143.9	144.0	144.1	144.0

Calculate the mean resistance of a single heating element.

[2]

What was the resolution of the digital multimeter used by the technician?

$Ω0.1\ \Omega$
$Ω0.5\ \Omega$
$Ω1.0\ \Omega$
$Ω144.0\ \Omega$

[1]

How do the results show that the technician's measurements were precise?

The measurements are close to the true value.
The measurements are grouped closely together.
The measurements are reproducible by other technicians.

[1]

How would a graph of mean total resistance against the number of elements show that the total resistance is directly proportional to the number of elements?

The plot gives a straight line that would pass through the origin.
The plot gives a curve that levels off at high numbers.
The plot gives a linear relationship with a positive y-intercept.

[1]

Predict the mean total resistance of 15 of these heating elements connected in series.

[2]

2.1 Current, potential difference and resistance

Question 20

Table 1

Markscheme

2.1 Current, potential difference and resistance

Question 20

Table 1

Markscheme

2.1 Current, potential difference and resistance

Question 20

Table 1

2.1 Current, potential difference and resistance Questions

2.1 Current, potential difference and resistance

Question 20

Table 1

2.1 Current, potential difference and resistance Questions