Class 10 : Practice Questions and Answers

A fuse is a safety device that breaks the circuit if the current exceeds a safe level, preventing damage to circuit components from overcurrent.

The atomic number is the number of protons in the nucleus. It defines the element and determines its position in the periodic table.

The chemical formula for water is $H_2O$, consisting of two hydrogen atoms and one oxygen atom.

Photosynthesis primarily occurs in the leaves, where chlorophyll absorbs sunlight to convert carbon dioxide and water into glucose and oxygen.

The digestive system breaks down food mechanically and chemically into smaller molecules, which are absorbed into the bloodstream for energy, growth, and repair. It involves the mouth, stomach, intestines, and organs like the liver and pancreas.

Coal is a non-renewable resource formed over millions of years from ancient plant matter. Once used up, it cannot be replaced on a human timescale, and its use contributes to environmental degradation.

The SI unit of force is the Newton (N). One Newton is the force required to accelerate a one-kilogram mass by one metre per second squared. It is a vector quantity with both magnitude and direction.

Copper is non-magnetic and does not exhibit magnetic properties. Iron, nickel, and cobalt are ferromagnetic materials that are attracted to magnets and can be magnetized.

The right-hand thumb rule determines the direction of the magnetic field around a current-carrying conductor. Point the thumb in the direction of current; the curled fingers indicate the field direction.

Using Ohm's law $V = I \times R$, we get $V = 2 \times 5 = 10$ V.

In a series circuit, total resistance is the sum of individual resistances. $2\Omega + 3\Omega + 5\Omega = 10\Omega$.

Violet light has the shortest wavelength in the visible spectrum, followed by blue, green, and red.

Electric motors operate on the magnetic effect of electric current. When current flows through a conductor in a magnetic field, the resulting force causes motion.

The force on the conductor is given by $F = B \times I \times L$.

$F = 0.5 \times 3 \times 2 = 3$ N

According to Ohm's law ($I = V/R$), if resistance is doubled while voltage remains constant, the current is halved.

Using the lens formula and magnification formula with magnification = -1.5 and object distance = 30 cm, the focal length works out to -45 cm.

When a wire is cut into equal parts, the resistance of each part equals the total resistance divided by the number of parts. $\frac{10}{5} = 2$ ohms.

The power of a lens is given by $P = \frac{1}{f}$, where f is in metres.

For f = 20 cm = 0.20 m:

$P = \frac{1}{0.20} = +5$ D

Electric potential difference (voltage) is measured in volts (V). It represents the energy difference per unit charge between two points in a circuit.

The commutator in a DC motor reverses the direction of current in the armature windings, ensuring continuous rotation in one direction.