Crookes four CRTs practical exam Flashcards
what was the aim of this investigation?
To observe discharge tubes with different set-ups to determine properties of cathod rays
what were the safety hazards surrounding this investigation and what were the safety precautions practice to help minimise these?
- high voltage sparks can inflict burns and pain on skin: teacher had performed this investigation infront of the class
- high voltage sparks will emit harmful x rays: 3m exclusion zone had been established between the apparatus(spark) and the rest of the class
what were the four cathode ray tubes used in this investigation and in what scenario were they placed?
- cathod ray tube with maltese cross placed in the middle of the tube
- cathode ray tube with glass paddlewheel mounted on runners inside the tube
- cathode ray tube with electric plates opposite eachother placed inside the tube. end of the tube was a fluorescent screen which lights up when the cathode rays achieve impact with the screen
- cathode ray tube with two opposite pole bar magnets placed either side of the tube
what occured during the paddlewheel CRT test and describe what these results suggest about cathode rays
when the cathode rays were emitted, the paddlewheel began to turn and move along its runners forward from the cathode toward the anode.
these results suggested the cathode rays were providing the wheel with momentum, momentum which is a property of particles with mass. the fact that the paddlewheel was moving from the cathode to the anode suggested the rays were both negatively charged and were being emitted from the cathode
what occured during the maltese cross test and decribe what this suggests about cathode rays
when a maltese cross had been placed in the middle of a cathode ray tube, the cross had obstructed the cathode rays being emitted. this produced a large shadow at the end of the tube due to this obstruction. the shadow had very sharp edges which suggested that diffraction was not occuring
1–> that cathode rays travel in straight lines. this supports both the wave and particle theories of cathode rays and 2–> cathode rays, because they hadnt been diffracting were not waves but particles
3–> the way in which the rays were creating a shadow of the maltese cross is wave like behaviour
what occured during the electric plate test and describe what this suggested about cathode rays
when two electric plates had been placed inside the tube, the cathode rays had been deflected in the direction of the positive plate: this indicated that the cathode rays were negatively charged particles, not waves because light itself is a wave and does not deflected in the presence of an electric field
the cathode rays were being emitted from the cathode perpendicularly, and because they were deflected toward the positive plate, this suggested the cathode rays were a stream of charged particles
upon impact on a fluorescent screen, the fluorescent screen lit up. this suggested that the cathode rays made of contituents which had energy and could cause chemical reactions
what occured during the magnetic field test and describe what this suggested about cathode rays
during this test, the stream of cathode rays were deflected in accordance with the right hand palm rule, indicating that a force was experienced by the cathode rays
this deflection had occured in accordance to the right hand palm rule, where the thumb was the direction of conventional current, meaning the opposite direction of the movement of the cathode rays. the fact that the rays had been deflected suggested that they were made of negatively charged particles.
