Which one of the following statements regarding cathode rays is not correct?
- (a)Cathode ray particles are electrons.
- (b)Cathode ray particles start from anode and move towards cathode.
- (c)In the absence of electrical and magnetic fields, cathode rays travel in straight lines.
- (d)Television picture tubes are cathode ray tubes.
Correct — B, 'Cathode ray particles start from anode and move towards cathode' — this is the statement that is not correct. Cathode rays are streams of electrons that originate at the cathode (the negative electrode) and travel towards the anode (the positive electrode), so the direction given in statement (b) is reversed. The other three statements are all true, which is why (b) is the exception the question asks for.
- (a)Cathode ray particles are electrons. — This is a true statement — J. J. Thomson showed cathode rays are streams of electrons — so it is not the incorrect one the question wants.
- (c)In the absence of electrical and magnetic fields, cathode rays travel in straight lines. — This is true — undeflected cathode rays move in straight lines and cast sharp shadows — so it is not the incorrect statement.
- (d)Television picture tubes are cathode ray tubes. — This is true — older televisions and monitors used cathode ray tubes (CRTs) — so it is not the incorrect statement.
Cathode rays are streams of electrons produced in a discharge tube at low pressure. They leave the cathode (negative electrode) and move towards the anode (positive electrode). They travel in straight lines when no field is applied and are deflected by electric and magnetic fields, which showed that they carry a negative charge.
The question asks for the wrong statement. Three of the four are standard true facts; the odd one out reverses the direction of travel. Fixing the start point (cathode) and destination (anode) is the whole trick.
- Cathode rays are streams of electrons emitted from the cathode (negative electrode).
- They travel from the cathode to the anode, in straight lines when no field is applied.
- They are deflected by electric and magnetic fields, showing a negative charge.
- The cathode ray tube (CRT) is the basis of older television and computer-monitor screens.
- Getting the direction wrong — cathode rays go from cathode to anode.
- Assuming cathode rays are electromagnetic waves; they are material particles (electrons).
Asked as a 'which statement is NOT correct' item on the nature, origin and direction of cathode rays.
No directly related past PYQ was found.
- practice — not a real PYQ
Cathode rays are streams of
- (a)protons
- (b)neutrons
- (c)electrons
- (d)photons
Answer(c) electrons — cathode rays were shown to be negatively charged electrons.
- practice — not a real PYQ
Cathode rays originate at the ____ and move towards the ____.
- (a)anode; cathode
- (b)cathode; anode
- (c)anode; anode
- (d)cathode; cathode
Answer(b) cathode; anode — from the negative electrode to the positive one.