2 (a) Diagram 1 shows the electrocardiogram (ECG) trace for a single heartbeat. On the vertical scale each square represents 0.2 mV. Complete the sentence by putting an (X) in the box next to your answer. The potential difference between R and S is about: A 0.9 mV B 1.8 mV C 9.0 mV D 1.8V (b) Diagram 2 shows the ECG trace for a heart that is beating too fast. The time between beats for this heart is 0.46 s. Calculate the frequency of the heartbeats. (i) frequency of heartbeats = __________ Hz (ii) When a heart is beating at a normal rate it has a frequency of 1.25 Hz. Calculate this heart rate in beats per minute. heart rate = _______________ beats per minute. (c) Suggest how good contact is made between the patient's skin and the electrodes of the ECG machine. (d) Describe what a pacemaker does when it is put inside the body of a patient.

GCSE Edexcel Physics Current: 2 (a) Diagram 1 shows the electr

2 (a) Diagram 1 shows the electrocardiogram (ECG) trace for a single heartbeat - Edexcel - GCSE Physics - Question 2 - 2016 - Paper 1

Question 2

2 (a) Diagram 1 shows the electrocardiogram (ECG) trace for a single heartbeat. On the vertical scale each square represents 0.2 mV. Complete the sentence by putting... show full transcript

Worked Solution & Example Answer:2 (a) Diagram 1 shows the electrocardiogram (ECG) trace for a single heartbeat - Edexcel - GCSE Physics - Question 2 - 2016 - Paper 1

Step 1

The potential difference between R and S is about:

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Answer

To find the potential difference between points R and S, we determine the value of the peak-to-peak amplitude. Since each square represents 0.2 mV, we can count the number of squares between R and S. Assuming it spans approximately 4.5 squares, we calculate the voltage as:

$ext{Voltage} = 4.5 ext{ squares} imes 0.2 ext{ mV/square} = 0.9 ext{ mV}$

Thus, the answer is A 0.9 mV.

Step 2

Calculate the frequency of the heartbeats.

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Answer

Frequency is calculated using the formula:

$ext{Frequency} = rac{1}{ ext{Time Period}}$

Given that the time between beats is 0.46 seconds:

$ext{Frequency} = rac{1}{0.46} ext{ Hz} \\ ext{Frequency} ext{ (in Hz)} hickapprox 2.17 ext{ Hz}$

Step 3

Calculate this heart rate in beats per minute.

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Answer

To convert frequency to heart rate in beats per minute, we use:

$ext{Heart Rate} = ext{Frequency} imes 60$

Using the frequency from part (b)(ii) of 1.25 Hz:

$ext{Heart Rate} = 1.25 ext{ Hz} imes 60 = 75 ext{ beats per minute}$

Step 4

Suggest how good contact is made between the patient's skin and the electrodes of the ECG machine.

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Answer

Good contact is achieved by ensuring the electrodes are properly adhered to the skin, often using conductive gel or adhesive patches that minimize impedance and facilitate transmission of the electrical signals from the heart.

Step 5

Describe what a pacemaker does when it is put inside the body of a patient.

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Answer

A pacemaker sends electrical signals to the heart, helping to regulate the heart rhythm. It detects heart rate and can deliver impulses to maintain a normal heartbeat, thus ensuring proper cardiac function.

2 (a) Diagram 1 shows the electrocardiogram (ECG) trace for a single heartbeat - Edexcel - GCSE Physics - Question 2 - 2016 - Paper 1

Worked Solution & Example Answer:2 (a) Diagram 1 shows the electrocardiogram (ECG) trace for a single heartbeat - Edexcel - GCSE Physics - Question 2 - 2016 - Paper 1

The potential difference between R and S is about:

Calculate the frequency of the heartbeats.

Calculate this heart rate in beats per minute.

Suggest how good contact is made between the patient's skin and the electrodes of the ECG machine.

Describe what a pacemaker does when it is put inside the body of a patient.

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