An X-ray can be deflected:
- A.by a magnetic field.
- B.by an electric field.
- C.by both electric and magnetic field.
- D.neither by electric field nor by magnetic field.
Correct answer
Explanation
The correct answer is D, neither by electric field nor by magnetic field. X-rays are electromagnetic waves made of uncharged photons, so electric and magnetic fields cannot bend them.
Electric and magnetic fields exert force only on charged particles: a charge q feels a force qE in an electric field and qvB in a magnetic field. X-rays, discovered by Wilhelm Röntgen in 1895, are high-energy electromagnetic radiation with wavelengths of roughly 0.01 to 10 nanometres, and their photons carry no charge. They therefore pass through these fields in a straight line. The same is true of gamma rays. By contrast, cathode rays (electrons) and alpha and beta particles are charged and are deflected.
A is wrong: a magnetic field deflects only moving charges, and X-rays carry no charge.
B is wrong: an electric field also acts only on charges.
C is wrong: neither field can deflect uncharged radiation.
Exam tip: not deflected = X-rays, gamma rays, neutrons; deflected = alpha, beta and cathode rays.
Practice Questions
View allConsider the following animals :
1. Hedgehog
2. Marmot
3. Pangolin
To reduce the chance of being captured by predators, which of the above organisms rolls up/roll up and protects/protect its/their vulnerable parts?
- A.1 and 2
- B.2 only
- C.3 only
- D.1 and 3
Show answer
Hedgehogs and pangolins curl into a tight ball when threatened, covering the soft belly and face with spines or scales; marmots do not.
Read the full explanation →Which one of the following is used in preparing a natural mosquito repellent?
- A.Congress grass
- B.Elephant grass
- C.Lemongrass
- D.Nut grass
Show answer
Lemongrass and its close relative citronella grass yield aromatic oils that keep mosquitoes away, so they are the base of many natural repellents.
Read the full explanation →Which one of the following devices is non-ohmic ?
- A.Conducting copper coil
- B.Electric heating coil
- C.Semi conductor diode
- D.Rheostat
Show answer
A diode does not obey Ohm's law: the current through it is not proportional to the voltage across it. An ohmic conductor gives a straight-line graph of current against voltage, so its resistance stays constant at a fixed temperature.
Read the full explanation →What is the formula mass of anhydrous sodium carbonate? (Given that the atomic masses of sodium, carbon and oxygen are 23 u, 12 u and 16 u respectively)
- A.286 u
- B.106 u
- C.83 u
- D.53 u
Show answer
Anhydrous sodium carbonate is Na₂CO₃, and 2 × 23 + 12 + 3 × 16 = 106 u. Formula mass is the sum of the atomic masses of all the atoms in one formula unit of an ionic compound.
Read the full explanation →Which one of the following minerals is used as a fuel in nuclear power stations ?
- A.Bauxite
- B.Quartz
- C.Feldspar
- D.Pitchblende
Show answer
Pitchblende, or uraninite, is the chief ore of uranium, the fuel used in most nuclear power stations. Pitchblende is a heavy, black mineral made mostly of uranium oxide.
Read the full explanation →