OAR Mechanical Comprehension: Electricity Flashcards
7 cards from real OAR practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 OAR Mechanical Comprehension: Electricity flashcards as text
A 60W bulb and a 100W bulb are connected in series. Which bulb glows brighter?
Answer: The 60W bulb
In series, the same current flows through both; the 60W bulb has higher resistance and dissipates more power (P = I²R).
What is the relationship between frequency and period of an AC waveform?
Answer: f = 1/T
Frequency and period are reciprocals: f = 1/T, where T is the time for one complete cycle.
What happens to resistance as the temperature of a metal conductor increases?
Answer: Resistance increases
In metals, higher temperature increases atomic vibration, impeding electron flow and raising resistance.
A 12V circuit draws 3A. A second identical load is added in parallel. What is the new total current?
Answer: 6A
Each parallel branch draws 3A, so total current doubles to 6A with two identical loads.
What is the standard frequency of AC power in the United States?
Answer: 60 Hz
US power grids operate at 60 Hz, meaning alternating current completes 60 cycles per second.
Which of the following best describes an electrical insulator?
Answer: A material that opposes electron flow strongly
Insulators have very few free electrons and high resistance, preventing significant current flow.
In a parallel circuit, if one branch is open (broken), what happens to the other branches?
Answer: The other branches continue operating normally
In a parallel circuit, each branch is independently connected to the voltage source, so other branches are unaffected by an open branch.