Theddy Physics Test

1. Q: What is Ohm’s Law?
   A: V=IRV=IR (Voltage = Current × Resistance).

2. Q: In a series circuit, which bulb is brightest?
   A: The one with the highest resistance (P=I2RP=I2R, same current).

3. Q: In a parallel circuit, which bulb is brightest?
   A: The one with the lowest resistance (P=V2RP=RV2​, same voltage).

4. Q: What is the formula for electrical power?
   A: P=IVP=IV, P=I2RP=I2R, or P=V2RP=RV2​.

5. Q: How does total resistance change in series vs. parallel?
   A: Series: Rtotal=R1+R2+...Rtotal​=R1​+R2​+.... Parallel: 1Rtotal=1R1+1R2+...Rtotal​1​=R1​1​+R2​1​+....

Magnets & Magnetism

6. Q: Why does a compass needle point north?
   A: Its north pole is attracted to Earth’s magnetic south pole (near geographic north).

7. Q: How do you magnetize an iron nail?
   A: Stroke it with a magnet in one direction or wrap it in a current-carrying coil.

8. Q: What is the energy conversion in a motor vs. a generator?
   A: Motor: Electrical → Mechanical. Generator: Mechanical → Electrical.

9. Q: What strengthens an electromagnet’s field?
   A: More coils, higher current, or a stronger core (e.g., iron).

10. Q: What creates Earth’s magnetic field?
    A: Molten iron moving in the outer core.

Nuclear Radioactivity

11. Q: How many protons, neutrons, and electrons are in helium-4 (⁴He)?
    A: 2 protons, 2 neutrons, 2 electrons.

12. Q: What is alpha decay?
    A: Emission of a helium nucleus (24He24​He) from an unstable atom.

13. Q: Which type of radiation has the most penetrating power?
    A: Gamma rays (stopped by thick lead/concrete).

14. Q: What is half-life?
    A: Time for half of a radioactive sample to decay.

15. Q: What distinguishes isotopes?
    A: Same protons (atomic number), different neutrons (mass number).

Bonus: Key Analogies & Mnemonics

16. Q: Voltage analogy:
    A: Water pressure in a hose (the “push”).

17. Q: Current analogy:
    A: Water flow rate in a hose (electrons moving).

18. Q: Motor vs. Generator mnemonic:
    A: Motor = Motion from electricity. Generator = Grid (electricity) from motion.

19. Q: Brightness in circuits:
    A: Series: I2RI2R. Parallel: V2RRV2​.

20. Q: Earth’s magnetic poles vs. geographic poles:
    A: Geographic North ≈ Magnetic South (compass points there).