SBA — Single Best Answer · Review
Question 586
Biophysics → General
Classification
Question
SSBAQuestion Header
Which combination most accurately describes an alpha particle?
Question Stem
Select the single best answer.
Options
A
Two protons and two neutrons, charge +2, highly ionising with low penetration
B
A high-speed negatively charged electron with high penetration
C
A positively charged particle approximately the size of an electron
D
A high-energy photon emitted from the nucleus
E
Electromagnetic radiation generated by decelerating electrons
Explanation
An alpha particle contains two protons and two neutrons, has a charge of +2 and a mass four times that of a proton. Alpha radiation is highly ionising but has very low penetrating power and can be stopped by air or skin.
Option Validity
B) A high-speed negatively charged electron describes beta radiation.
C) A positively charged particle approximately the size of an electron is a positron.
D) A high-energy photon emitted from the nucleus describes gamma radiation.
E) Electromagnetic radiation generated by electron deceleration describes X-radiation, including Bremsstrahlung.
Further Reading
Saxena R. Textbook for MRCOG-1. Chapter 9: Biophysics, pp.278–279.