Identifying diode, LED, resistor and capacitor — practice questions

Question 1 · difficulty L1 · recall

A resistor is commonly identified by

• A. a transparent light-emitting lens only
• B. a polarity stripe marking a cathode on every resistor
• C. colour bands or printed resistance markings
• D. two unequal capacitor plates visible externally

Question 2 · difficulty L1 · understanding

A typical LED can often be identified by

• A. having no p-n junction
• B. being a nonpolar fixed resistor
• C. showing identical behaviour in both directions
• D. a light-emitting package and polarity-sensitive leads

Question 3 · difficulty L2 · understanding

An ordinary semiconductor diode is a

• A. two-terminal polarity-sensitive p-n junction device
• B. nonpolar resistor
• C. three-terminal transistor only
• D. mechanical switch

Question 4 · difficulty L2 · application

A capacitor is primarily used to

• A. produce radioactive decay
• B. store electric charge and energy in an electric field
• C. measure magnetic declination
• D. act as a perfect DC conductor indefinitely

Question 5 · difficulty L3 · application

Using a multimeter diode-test mode, a healthy silicon diode typically shows

• A. the same low resistance in both directions
• B. zero voltage in both directions always
• C. a forward drop in one direction and open/high reading in the reverse direction
• D. light emission necessarily even for any diode

Question 6 · difficulty L3 · application

A resistor measured with an ohmmeter should ideally give

• A. opposite signs of resistance
• B. a forward diode drop only one way
• C. infinite resistance one way and zero the other
• D. approximately the same resistance when leads are reversed

Question 7 · difficulty L4 · analysis

A polar electrolytic capacitor should be connected with

• A. correct polarity according to its markings
• B. either polarity at any voltage without concern
• C. its two leads shorted
• D. the positive lead always to ground

Question 8 · difficulty L4 · analysis

An LED does not light in a simple low-voltage test even though forward biased. One reasonable explanation is

• A. all forward-biased LEDs must light at zero voltage
• B. the available current is too small or the LED threshold is not reached
• C. the LED must therefore be a resistor
• D. polarity is irrelevant

Question 9 · difficulty L5 · analysis

A component shows very high resistance initially on an ohmmeter, then the reading changes as it charges. This behaviour suggests

• A. a fixed resistor only
• B. a mechanical ruler
• C. a capacitor
• D. a bar magnet

Question 10 · difficulty L5 · analysis

Four unlabeled components are tested: one is nonpolar with stable resistance, one conducts mainly one way, one emits light in forward conduction, and one shows charging behaviour. They are respectively

• A. capacitor, resistor, diode, LED
• B. diode, capacitor, resistor, LED
• C. LED, resistor, capacitor, diode
• D. resistor, diode, LED, capacitor