One-half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.
Yes, The convex lens will form a complete image of an object, even if its one half is covered with black paper. It can be experimentally verified:.
In first Case
If the upper half of the lens is covered then a ray of light coming from the object will be refracted by the lower half of the lens and these rays meet at the other side of the lens to form the image of an object,
In Second Case
When the lower half of the lens is covered then a ray of light coming from the object is refracted by the upper half of the lens and these rays meet at the other side of the lens to form the image of the given object.
When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.
Outline a project which aims to find the dominant coat colour in dogs.
Draw the structure for the following compounds.
(i) Ethanoic acid (ii) Bromopentane*
(iii) Butanone (iv) Hexanal.
*Are structural isomers possible for bromopentane?
A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?
How is the sex of the child determined in human beings?
(a) What property do all elements in the same column of the Periodic Table as boron have in common?
(b) What property do all elements in the same column of the Periodic Table as fluorine have in common?
Calculate the number of electrons constituting one coulomb of charge.
What is an homologous series? Explain with an example.
Why is variation beneficial to the species but not necessarily for the individual?
A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?
(i) Write the electron-dot structures for sodium, oxygen and magnesium.
(ii) Show the formation of Na2O and MgO by the transfer of electrons.
(iii) What are the ions present in these compounds?
Let the resistance of an electrical component remains constant while the potential difference across the two ends of the component decreases to half of its former value. What change will occur in the current through it?
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.
Metal | Iron(II) sulphate | Cooper(II) sulphate | Zinc sulphate | Silver nitrate |
A | No reaction | Displacement | ||
B | Displacement | No reaction | Displacement | |
C | No reaction | No reaction | No reaction | No reaction |
How does chemical coordination take place in animals?
Why should we conserve forests and wildlife?
Draw a labelled diagram of the longitudinal section of a flower.
Use Mendeléev’s Periodic Table to predict the formulae for the oxides of the following elements:
K, C, AI, Si, Ba.
How are the alveoli designed to maximise the exchange of gases?
When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.