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(a) Diagram 1 shows the electrocardiogram (ECG) trace for a single heartbeat - Edexcel - GCSE Physics - Question 2 - 2016 - Paper 1
Question 2
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(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
The potential difference between R and S is approximately 1.8 mV. This is calculated by counting the number of squares between R and S, which is 9 squares, and multiplying by the vertical scale of 0.2 mV per square:
9extsquaresimes0.2extmV/square=1.8extmV
Step 2
Calculate the frequency of the heartbeats.
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Answer
The frequency of the heartbeats can be calculated using the formula:
ext{Frequency} = rac{1}{ ext{Time period}}
Given that the time between beats is 0.46 seconds:
ightarrow 2.17 ext{ Hz}$$
Step 3
Calculate this heart rate in beats per minute.
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Answer
To convert frequency in Hz to heart rate in beats per minute, use:
extHeartRate(bpm)=extFrequency(Hz)imes60
Substituting the normal heart frequency:
1.25extHzimes60=75extbeatsperminute
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 can be achieved by ensuring the electrodes are properly cleaned and conductive gel is used to reduce any noise and improve the quality of the signals captured by the ECG machine.
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/pulses to the patient to regulate the heart rhythm. It detects the heart rate and ensures the heart beats at a normal rate, thereby maintaining an appropriate heart rhythm.
