A toaster produces more heat than a light bulb, when connected in parallel across a source of e.m.f. Which has greater resistace and why?

A toaster produces more heat than a light bulb when they are connected in parallel. Which has the greater resistance.

A conductor of length L is connected across a dc source of e.m.f E. If the conductor is replaced by another of the same materials and area of cross-section but of length 5 L, by what factor will the drift velocity change?

An electric lamp of 200 ohm and a toaster of 100 ohm are connected in parallel to a 220 V electricity source. What will be resistance of an electric iron which when connected to the same electric source permits the same current as the total current flowing through both the appliances described above?

An e.m.f. is produced in a coil, which is not connected to an external voltage source. This can be due to

A number of identical cells, n , each of e.m.f. E, internal resistance r connected in series are charged by a d.c. source of e.m.f. E', using a resitor R Deduce the expresison for the charging current and the potential difference across the combination of the cells.

Direction. In the following questions, a statement of assertion is followed by a statement of reason. While answering a question, you are required to choose the correct are out of the given four responses and mark it as (A). If both assertion and reason are true and reason is the correct explanation of the assertion, (B) if both assertion and reason are true but reason is not correct explanation of the assertion. (C) if assertion is true, but reason if false, (D) if both assertion and reason are false Assertion : We use a thick wire in the secondary of a step down transformer to reduce the production of heat. Reason : When the plane of the armature is parallel to the lines of force of magnetic field, the magnitude of induced e.m.f. is maximum.

A potentiometer wire carries current. The potential difference across 70 cm of its balances the potential difference across a 2 ohm coil supllied by a cell of e.m.f. 2 volt. When a 1 ohm coil is placed in parallel with the 2 ohm coil, a length equal to 50 cm of the potentiometer wire is required to balance the potential difference across the parallel combination. What is the internal resistance of the 2 V cell?

Consider the following four statements (A-D) and select the option which includes all the correct ones only: Single cell Spirullina can produce large quantities of food rich in proteins, minerlas, vitamins, etc. Body weightwise, the micro-organism Methylophilus methylotrophus may be able to produce several time more proteins than the cows per day Common button mushrooms are a very rich source of vitamin-C A rice variety has been developed which is very rich in calcium.

A 2 mu F capacitor 100 ohm resistor and 8 H inductor are connected in series with an a.c. source. What should be the frequency of soure for which the current drawn in the circuit is maximum? If peak value of emf of the source is 200 V, What is the phase relation between voltages across inductor and resistor ?

The existence of negatively charged particle in an atom was shown by J.J. Thomson as a result of the studies of the passage of electricity through gases at extremely low pressure known as discharge tube experiments. When a high voltage of the order of 10,000 volts or more was impressed across the electrodes, some sort of invisible rays moved from the negative electrode to the positive electrode these rays are called as cathode rays. Cathode rays travel in straight path in absence of electrical and magnetic field . Cathode rays consist of material part and charged particles? Cathode rays produce X-rays and light is emitted when they strike on ZnS screen. Cathode rays penetrate through thin sheets of aluminium and other metals . They affect the photogenic plate and passes heating effect when they strike on metal foil. The raito of charge to mass i.e charge/mass is same for all the cathode rays irrespective of the gas used in the tube. The existence of positively charged particle in an atom was shown be E. Goldstein. He repeated the same discharge tube experiments by using a perforated cathode. It was observed that when a high potential difference was applied between the electrodes, not only cathode rays were produced but also a new type of rays were produced simultaneoulsy from anode moving towards cathode and passes through the holes or canal of the cathode. These termed as canal rays or anode rays. These rays travel in straight lines and consists of positively charged particles. These rays have kinetic energy and produces heating effect also. The e/m ratio of these rays is smaller than that of electrons. Unlike cathode rays, their e/m value is dependent upon the nature of the gas taken in the tube. These rays produced flashes of light on ZnS screen and can pass throughs thin metal foils. They can produce physical and chemical changes and are capable to produce ionisation in gases. For cathode rays the value of e/m: