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When the source of a sound wave vibrates, the surrounding particles are disturbed and vibrates in a direction parallel to the direction of the sound waves.
The vibrations are passed on from one particle to the next in a series of alternate regions of compressions and rarefactions, transmitting the sound waves through the medium.
The apparatus is set up as shown in the diagram below.
The initial mass of the reaction system is recorded.
The thread is pulled to mix the calcium carbonate and acid. The stopwatch is started at the same time.
The mass of the reaction system is recorded every one-minute.
From the data collected, a graph of mass of reaction system against time taken is plotted.
From the slope of the graph, the speed of reaction can be studied.
The steeper the gradient of the graph, the faster the speed of reaction.
The apparatus is set up as shown in the diagram below.
The thread is pulled to mix the magnesium ribbon and acid. The stopwatch is started at the same time.
The volume of hydrogen collected in the gas syringe is recorded every half-minute.
From the data collected, a graph of volume of gas produced against time taken is plotted.
From the slope of the graph, the speed of reaction can be studied.
The steeper the gradient of the graph, the faster the speed of reaction.
Copper (II) nitrate is an ionic compound. In the solid state, the ions of copper (II) nitrate are held in fixed positions in a giant ionic lattice structure. There are no mobile ions to conduct electricity.
In the molten or aqueous state, the giant ionic lattice structure is broken down. The ions are now able to move about. These mobile ions can act as charge carriers.
a) The force on XY is acting downwards.
Applying Fleming’s Left Hand Rule, the middle finger points into the page, in the direction of the current flow from X to Y, the index finger points to the right, in the direction of the magnetic field, the thumb will be pointing downwards, which represents the direction of the force on XY.
b) (i) Pan moves upwards.
b) (ii) When the magnets are brought closer together, the magnetic field strength of the magnet increases, increasing downwards force on XY. The greater clockwise moment will then cause the pan to tilt upwards.
c) (i) When an alternating current flows through the iron bar, a rate of change of magnetic field is produced by the iron bar. The rate of change of magnetic field produced an induced electromotive force in the flat coil, and hence an induced current flow through the closed circuit of the coil, causing the lamp to light up.
c) (ii) The lamp will be dimmer.
The lower frequency produced a lower rate of change of magnetic field, which produce a lower electromotive force in the flat coil, causing the voltage supplied to lamp to decrease.
Click on the title of this posting to see the question and worked solution.
One of my students told me a similar vector question came out in this year’s A level P2.
Luckily we went through this question one day before the paper. Yeah!
An alternative method to solve the question is also provided.
Click on the title of this posting to see the question and worked solution.
Many students have problems with solving part (iii) of the question.
It is easier to solve with the aid of a Venn Diagram. Once the required region is identified, think of the possible events that can occur within that region, and come out with the required probabilities. If you are still having problems, whatsapp me! 🙂