Capacitors in electrocardiography monitors
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- Capacitors in electrocardiography monitors
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Capacitors in electrocardiography monitors
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[post_date] => 2025-01-09 08:01:19
[post_date_gmt] => 2025-01-09 13:01:19
[post_content] => Practice Passage (Question 1-4)
*This passage is the property of Khan Academy and has been reformatted into an AAMC-style interface in their entirety by MedLife Mastery. MedLife Mastery does not endorse and is not an affiliate of Khan Academy.
A heart monitor detects the functional soundness of the patient’s heart. Nodes are attached to a patient’s skin, which in turn is able to pick up cardiac electrical activity. These nodes then relay this information to the main monitor, which displays it accordingly.
A technician is working at a hospital with similar machines, referred to as electrocardiography (ECG) monitors. The monitoring equipment that the hospital uses has a single 12F capacitor within. When the ECG is in use, the 12F capacitor is subjected to a voltage of 3V.
The monitoring equipment functions properly during the first portion of the day. However, later in the day the 12F capacitor in one of the ECG monitors burns out.
After looking in the electronics storeroom, the technician realizes the hospital does not have any extra working 12F capacitors available. All the hospital has are the following capacitors:
Figure 1. The capacitors available at the technician’s disposal.
This activates transducin, leading to the activation of cGMP phosphodiesterase, the hydrolyzation of cGMP, and the closing of cGMP dependent Ca++/Na+ channels.
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[questions] => Array
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[quiz_unique_key] => 578908434
[question] => Of the available capacitors, which could you connect in parallel to replace one of the burned out capacitors?
[value] => Array
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[answer] => 4
[description] => Reason for the Correct Answer:
For parallel capacitors, you can add individual capacitors to find the equivalent capacitance
Which capacitors would add up to the original capacitor
Since 2F + 4F + 6F adds up to 12F, they could be connected in parallel to form a capacitor equivalent to the 12F capacitor
)
[answers] => Array
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[0] => Array
(
[each_answer] => A. 20F, 30F
)
[1] => Array
(
[each_answer] => B. 4F, 6F, 20F
)
[2] => Array
(
[each_answer] => C. 1F, 2F, 4F, 6F
)
[3] => Array
(
[each_answer] => D. 2F, 4F, 6F
)
)
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[1] => Array
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[quiz_unique_key] => 3873426850
[question] => Of the available capacitors, which could you connect in series to replace one of the burned out capacitors.
[value] => Array
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[answer] => 3
[description] => Reason for the Correct Answer:
For series capacitors, you can use 1/Ceq = 1/C1+1/C2+… to find the equivalent capacitance.
Consider which capacitors could you use for C1 and C2 that would give an equivalent capacitance of the original 12F capacitor.
Since the inverse of 1/20F + 1/30F gives 12F, they could be connected in series to form a capacitor equivalent to the 12F capacitor.
)
[answers] => Array
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[0] => Array
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[each_answer] => A. 2F, 4F, 6F
)
[1] => Array
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[each_answer] => B. 1F, 2F, 4F, 6F
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[2] => Array
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[each_answer] => C. 20F, 30F
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[3] => Array
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[each_answer] => D. 4F, 6F, 20F
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[2] => Array
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[quiz_unique_key] => 83407773
[question] => If you were to remove the built in dielectric (with dielectric constant 6) from one of the 12F capacitors, which would occur?
[value] => Array
(
[answer] => 2
[description] => Reason for the Correct Answer:
When dielectrics are inserted into a capacitor, they always increase the capacitance.
In this scenario we are removing a dielectric from a capacitor.
Since adding a dielectric always increases the capacitance, and we removed a dielectric from a capacitor, the capacitance must go down.
)
[answers] => Array
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[0] => Array
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[each_answer] => A. The capacitance would decrease to 0F, since capacitors can’t function without a dielectric
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[1] => Array
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[each_answer] => B. The capacitance would decrease to 2F
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[2] => Array
(
[each_answer] => C. The capacitance would increase to 24F
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[3] => Array
(
[each_answer] => D. The capacitance would remain the same, 12F
)
)
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[3] => Array
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[quiz_unique_key] => 2261298308
[question] => In the properly functioning monitoring equipment, what is the energy stored by the 12F capacitor?
[value] => Array
(
[answer] => 2
[description] => Reason for the Correct Answer:
The energy stored in a capacitor is E=1/2 CV2
We’re told that the capacitor is subjected to a voltage of 3V
Plug in the capacitance of 12F for C, and the voltage of 3V for V. Then solve for E
)
[answers] => Array
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[0] => Array
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[each_answer] => A. 108J
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[1] => Array
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[each_answer] => B. 54J
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[2] => Array
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[each_answer] => C. 18J
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[3] => Array
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[each_answer] => D. 36J
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[4] => Array
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[quiz_unique_key] => 2151129325
[question] => In the properly functioning monitoring equipment, what is the charge stored by the 12F capacitor?
[value] => Array
(
[answer] => 3
[description] => Reason for the Correct Answer:
The definition of capacitance is C=Q/V
We’re told that the capacitor is subjected to a voltage of 3V
Plug in the capacitance of 12F for C, and the voltage of 3V for V. Then solve for Q
)
[answers] => Array
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[0] => Array
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[each_answer] => A. 0.25C
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[1] => Array
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[each_answer] => B. 4C
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[2] => Array
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[each_answer] => C. 36C
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[3] => Array
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[each_answer] => D. 12C
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[558923|1] => D
[558923|2] => C
[558923|3] => B
[558923|4] => B
[558923|5] => C
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