An object is placed before a convex lens and its real image is obtained. Now if half of the surface is covered with paper. The result will be :

If the protons and electrons are the only basic charges in the universe, all the observable charges have to be integral multiples of e. Thus, if an object contains x electrons and y protons, the net charge on the object will be

The power and aperture of lenses L1, L2 and L3 are given below in tabular format. Which pair of lenses should be chosen for constructing a microscope?

Lens	Power	Aperture
L1	3D	8 cm
L2	6D	1 cm
L3	10D	1 cm

An electric dipole is placed at an angle of \(30^\circ\) with an electric field of intensity \(3 \times 10^5 \text{ N/C}\). It experiences a torque equal to \(6 \text{ N m}\). If the dipole length is 2 cm, the value of charge will be

Magnetic moment of a thin bar magnet is 'M'. If it is bent into a semicircular form, its new magnetic moment will be :

A uniform electric field exists in the positive x-direction. Let \( V_A = \) electric potential at (0, 0, 0) cm, \( V_B = \) electric potential at (5, 0, 0) cm and \( V_C = \) electric potential at (0, 5, 0) cm. The correct relationship between them is :

A p-n junction diode can be used :

According to Arrhenius equation \(k=A e^{-\frac{E_a}{R T}}\). If In k vs 1/T graph plotted, what will be the intercept of this plot?

A pipe can fill a tank in 2 hours. Because of a leak in the tank, the pipe takes 2 hours 40 minutes to fill the tank. The time the leakage takes to empty the full tank is :

At one place on earth, the resultant magnetic field is 0.25 G and the angle of dip is 45°. The horizontal component of earth's magnetic field will be

The conversions which are represented correctly are
(A)

(B)

(C)

(D)

Choose the correct answer from the options given below:

Read the following passage carefully and answer the given questions.
Plasmodium, a tiny protozoan is responsible for the disease malaria. Different species of Plasmodium (P. vivax, P. malaria and P. falciparum) are responsible for different types of malaria. Of these, malignant malaria caused by Plasmodium falciparum is the most serious one and can even be fatal. Innate immunity consist of four types of barriers. These are – (i) Physical barriers- skin on our body is the main barrier which prevents entry of the micro-organisms. (ii) Physiological barriers- Acid in the stomach, saliva in the mouth, tears from eyes-all prevent microbial growth. (iii) Cellular barriers- Certain types of leukocytes (WBC) of our body like polymorpho-nuclear leukocytes (PMNL-neutrophils) and monocytes and natural killer (type of lymphocytes) in the blood as well as macrophages in tissues can phagocytose and destroy microbes. (iv) Cytokine barriers- virus-infected cells secrete proteins called interferons which protect non-infected cells from further viral infection. Allergy is due to the release of chemicals like histamine and serotonin from the mast cells. The use of drugs like anti-histamine, adrenalin and steroids quickly reduce the symptoms of allergy. Drugs like barbiturates, amphetamines, benzodiazepines, and other similar drugs, that are normally used as medicines to help patients cope with mental illnesses like depression and insomnia, are often abused.
Which one of the followings is not an example of physiological barriers?

The acute angle between the lines \(\vec{r}=(4 \hat{i}-\hat{j})+\lambda(2 \hat{i}+\hat{j}-3 \hat{k})\) and \(\frac{x-1}{1}=\frac{y+1}{-3}=\frac{z-2}{2}\) is