If two thin convex lenses are kept in contact, the focal length of the combination is :

Identify the correct statement(s) among the following:
(A) The time taken by a light wave is \( 5 \times 10^{-9} \text{ s} \) to travel a thickness of 1 cm of glass having refractive index 1.5.
(B) Two similar waves of amplitude 3 mm and 5 mm reach a point in the same phase. The resultant amplitude will be 8 mm.
(C) Two waves of amplitude 2 mm each reach a point with a phase difference of \( \pi/2 \). The resultant amplitude is zero.
(D) If one of the slits is closed in Young's double slit experiment, the interference pattern will disappear.
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Which of the following can produce virtual image larger than the object?

The magnetic flux (Φ) through the area of cross-section of a current-carrying coil is proportional to the current (i) i.e., Φ = Li.
(A) L is self-inductance of the coil
(B) The self-inductance of the coil does not depend on its geometry
(C) self-inductance is the electromagnetic analogue of mass in mechanics
(D) The self-inductance of the coil depends on the permeability of the medium inside coil
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The mass defect (\( \Delta M \)) for a nucleus of mass number (A), atomic number (Z) and mass (M) is given by:

When a potential difference is applied across the ends of a conductor, the electric field exists :

The correct sequence A, B, C, D, E with reference to atomic spectral series is :
(A) Lyman series \(\frac{1}{\lambda}=R\left(\frac{1}{A^2}-\frac{1}{n^2}\right)\)
(B) Balmer series \(\frac{1}{\lambda}=R\left(\frac{1}{B^2}-\frac{1}{n^2}\right)\)
(C) Pfund series \(\frac{1}{\lambda}=R\left(\frac{1}{C^2}-\frac{1}{n^2}\right)\)
(D) Brackett series \(\frac{1}{\lambda}=R\left(\frac{1}{D^2}-\frac{1}{n^2}\right)\)
(E) Paschen series \(\frac{1}{\lambda}=R\left(\frac{1}{E^2}-\frac{1}{n^2}\right)\)
Choose the correct answer from the options given below :

In a magnetic field,
(A) a charged particle in motion can experience a force
(B) a charged particle at rest, experiences a force
(C) there is no change in the speed of the charged particle
(D) there is a change in the kinetic energy of the charged particle.
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The half life of a radioactive substance is 30 s. Calculate the time taken for the sample to decay to \( \frac{3}{4} \) th its initial value.

A closed circuit in the form of a regular hexagon of side a carries a current I. What is the magnetic field at the centre of the hexagon?

Read the given passage carefully and answer the questions
Salmonella typhi is a pathogenic bacterium which causes typhoid fever in human beings. Sustained high fever (39° to 40°C), weakness, stomach pain, constipation, headache and loss of appetite are some of the common symptoms of this disease. Typhoid fever could be confirmed by Widal test. Plasmodium enters the human body as sporozoites. The parasites initially multiply within the liver cells and then attack the red blood cells (RBCs) resulting in their rupture. The rupture of RBCs is associated with release of a toxic substance, haemozoin, which is responsible for the chill and high fever recurring every three to four days. There is lymphoid tissue also located within the lining of the major tracts (respiratory, digestive and urogenital tracts) called mucosa-associated lymphoid tissue (MALT). In our body, cell growth and differentiation is highly controlled and regulated. In cancer cells, there is breakdown of regulatory mechanisms. Normal cells show a property called contact inhibition by virtue of which contact with other cells inhibits their uncontrolled growth. Cancerous cells just continue to divide giving rise to masses of cells called tumors. Tumors are of two types: benign and malignant. Cannabinoids are a group of chemicals, which interact with cannabinoid receptors present principally in the brain. Generally taken by inhalation and oral ingestion, these are known for their effects on cardiovascular system of the body.
Which one of the following statements is not true?

If \(A=\left[\begin{array}{cc}1 & 0 \\ 0 & -1\end{array}\right]\) and \(B=\left[\begin{array}{ll}0 & 1 \\ 1 & 0\end{array}\right]\) then the matrix \(A B\) is equal to:

Factors that do not affect Hardy-Weinberg equilibrium are:
(A). Genetic drift
(B). Mitosis
(C). Genetic recombination and natural selection
(D). Pleiotropy
Choose the correct answer from the options given below: