Types of Radioactive Decay AP Physics 2 FRQ

Types of Radioactive Decay AP Physics 2 FRQ – Exam Style Questions etc.

Types of Radioactive Decay AP Physics 2 FRQ

Unit 15: Modern Physics

Weightage : 15–18%

AP Physics 2 Exam Style Questions – All Topics

Question

$
{ }_{83}^{214} \mathrm{Bi} \rightarrow \mathrm{X}+\beta^{+}
$

In the decay represented above, what is the nucleon number of particle $\mathrm{X}$ ?
(A) 82

(B) 83

(D) 214

▶️Answer/Explanation

Ans:D

Question

The following equation represents positronelectron annihilation, in which a positron and an electron become two photons.
$
e^{+}+e^{-} \rightarrow \gamma_1+\gamma_2
$

Which of the following correctly explains a reason why the interaction is possible?

(A) The photons have no charge, so total charge is conserved.

(B) Two particles become two particles, so the number of particles is conserved.

(D) Each particle has the same kinetic energy.

▶️Answer/Explanation

Ans:A

Questions

A nucleus of $_{92}^{238}\textrm{U}$ undergoes a series of decays in which it emits eight $_{2}^{4}\textrm{He}$ nuclei and some $\beta ^{-}$ particles to produce the nucleus $_{82}^{206}\textrm{Pb}$ . . How many $\beta ^{-}$ particles are emitted in the process?

(A) 10
(B) 8
(C) 6
(D) 5

▶️Answer/Explanation

Ans: C

This option is correct. Because beta particles do not have mass number, conservation of charge is used to balance the reaction. The change in atomic number from the element uranium (U) to lead (Pb) is a reduction of 10 positive charges. The eight heliums (He) account for production of 16 positive charges, so there needs to be 6 negative charges $\beta ^{-}$ emitted also for a net change of zero.

Questions

A scientist is studying the radioactive decay of an element and wants to determine the sign of some of the particles emitted. The scientist lets a beam of the particles, all with the same speed,
pass through an opening in a shield and enter the field created by a wire carrying a constant current. Paths 1 and 2 represent the observed paths of the particles. Based on the paths, which of the following could be the types of particles?

Path 1 Particle Path 2 Particle

(A) Electron Alpha
(B) Alpha Electron
(C) Positron Alpha
(D) Alpha Positron

▶️Answer/Explanation

Ans: C

This option is correct. Using a right hand rule to determine force exerted on a charged particle moving in a magnetic field, the force is in the same direction on both particles only if they have the same type of charge. Setting the expression for centripetal force equal to magnetic force, the radius of curvature is equal to $\frac{mv}{qB}$ . Both the alpha and positron are positive, but the alpha has twice the charge and four times the mass, so the alpha takes path 2 with a larger radius.

Question

In each of the nuclear reactions given below, a product is indicated by the letter X. In which of the reactions does the letter X represent a positron? (A positron is a positively charged particle with the same mass and magnitude of charge as an electron.)

Answer/Explanation

Ans:B

Types of Radioactive Decay AP Physics 2 FRQ